This paper used a simply supported beam as a study objective, and set up the finite element model of the beam by PATRAN to obtain the simulating displacement response of the beam. The code was written in MATLAB to identify the location of the dynamic load acting on the beam. This paper proposed a fast method based on the minimum discriminate coefficient method , and it identified the the location of the dynamic load by the way of gradually approach. Compared with the common method, this method cut back the calculation process and time by reduce the division of the finite elements. Simulation showed that this fast method reduced the time of calculation with ensuring the accuracy and exactness of the identification, which brought convenience to the work of identifying dynamic loads.