Whether to choose intra-or inter-regional R&D collaboration is a very important part of firms’ open innovation strategy. This paper systematically describes the mechanism for firms’ intra-or inter-regional R&D collaboration on innovative performance, as well as the moderating effect of technology diversification, and meanwhile verifies the hypotheses by using negative binomial regression models and data about listed firms in the electric vehicle industry. The results show that firms’ intra-or inter-regional R&D collaborations both have a significantly positive impact on innovative performance. Specifically, intra-regional R&D collaboration promotes innovative quantity, while inter-regional R&D collaboration benefits innovative quality. The moderating effects of technology diversification are significantly negative.