For a signal intersection, the calculating value of traffic capadty is discrepant under different calculation methods. Taking two typical signal intersections of Wuhan for examples, three common methods (Norm Method, Stop-line Method, and Saturation Flow Rate Method) are used to calculate the traffic capacity respectively. And the calculated result is compared with the measured traffic capacity, so as to explore the most suited calculating method of traffic capacity for the native mixed traffic flow. Finally by analyzing this paper advanced the suggestions about how to choose traffic capacity'...