Innovation is the first driving force leading development, and the importance of innovation ability in enterprise competition is becoming increasingly prominent. However, independent innovation is often risky and has a long cycle. Innovation activities may occupy a lot of resources and funds in their daily business activities, and once the innovation fails, enterprises may be under pressure from the collapse of stock prices in the capital market and the tightening of financing constraints. Therefore, for many listed companies that lack the ability of independent innovation, internal innovation is often powerless. At this time, M&A has become an important means to quickly realize external innovation. The ways of M&A to promote enterprise innovation mainly include selecting the target enterprise with high innovation ability and realizing collaborative innovation with the target enterprise, that is, selection channel and synergy channel. However, there is few literatures to distinguish these two M&A innovation channels, and the tendency of Chinese listed companies in the selection of M&A objects is unknown. Relying on the selection channel and synergy channel framework of M&A for innovation, this paper verifies the internal mechanism of M&A premium and innovation ability, and enriches the relevant research of agency theory, resource acquisition theory and synergy theory in M&A motivation theory.
     This paper takes A-share listed companies from 2007 to 2017 as a sample. In terms of index selection, through the test of the relationship between M&A premium and the innovation ability of the merging enterprises before M&A, it is found that when the innovation ability of the merging enterprises is weak, they tend to pay a higher premium, and the level of innovation ability is often consistent between years. At this time, if there is a simple regression between M&A premium and enterprise innovation ability after M&A, there may be a certain reverse causality problem. This paper takes incremental innovation before and after M&A as the measurement index of innovation ability improvement. This method can alleviate the possibility of reverse causality to a great extent and enhance the credibility of the conclusion. At the same time, this paper takes the industry average of M&A premium as the instrumental variable of M&A premium for endogenous test, which alleviates the problems of missing variables to a great extent. 
    The study found that: (1) compared with the innovation ability of the merging enterprises before M&A, the higher the M&A premium, the stronger the overall innovation ability of the enterprises after M&A, that is, the M&A premium supports the selection channel of M&A innovation. (2) Compared with the innovation ability of both sides before M&A, there is no significant correlation between M&A premium and incremental innovation generated by synergy after M&A, that is, M&A premium does not support the synergy channel of M&A innovation. (3) Further research shows that when the target enterprise is a high-tech enterprise, its M&A premium is significantly higher, which supports the selection channels from a more direct perspective. The regression between the M&A premium and the innovation ability of the merging enterprises after M&A shows that the higher the M&A premium, the lower the innovation ability of the merging enterprises after M&A, which also falsifies the synergy channel again. (4) In order to control the impact of M&A events on the innovation output of enterprises, the sample range is limited to the enterprises with M&A in that year. In order to answer the question whether the high premium of M&A enterprises will have a negative impact on the innovation of enterprises compared with enterprises without M&A. After matching the successful M&A enterprises with the failed M&A enterprises, this paper finds that even in the full sample range, high premium payment can still bring high innovation output to enterprises.
    This paper reveals the tendency of listed companies in the choice of M&A innovation channels. Compared with the target high-tech enterprises, the M&A cost of selecting non-high-tech companies with synergy innovation ability is lower and makes a greater contribution to the realization of the overall innovation ability of the society. However, at present, Chinese listed companies still have a certain shortsightedness in the selection of M&A targets. Therefore, it is suggested that enterprises should pay more attention to the synergy between enterprises during and after M&A, rather than only the innovation ability of the target enterprise. Regulators need to strengthen the supervision of high premium M&A, so as to prevent the possible harm to the operation of listed companies.