Abstract: By using the data from year of 1978 to 2004(total 27 years), it is found that Chinese three main industries have a close inherent link.From the perspective of system dynamics, an industry development is not only related to the preliminary development of the industry but also related to the early stage and the same period development speed of other industries.From the impulse response function and variance decomposition results, it is found that the importance of chief industry represented by agriculture is very clear. The development of agriculture is very important to the develoopment of itself, and secondary, tertiary industries.