Dimensional chain calculation plays an extremely important role in martial productions, particularly auto weapon design. In order to performance higher efficiency, reduce mistakes and realize computerized course of calculation, is vector organum method introduced in calculations. How to directly get dimension information from split graph of assembling graph, and create equations automatically by vector organum method are introduced. The results of application indicate that the method suits any case of split graph of assembling graph, can relieve fatigue of the engineers, and got perfect effects.