In this paper, the testing by load of bridge structures, is given. In the theoretical part of the paper, the standard for load testing of the structures is elaborated, as well as the method of modeling for the purpose of testing by load, while in the practical part, a test program for test by load of a composite bridge, is presented. In the practical part, the calculations of a bridge structure for the design load, was made, where, based on the traffic load, the intensity of the test load was determined. For the purpose of test by load, three axle trucks are being used, that represent load in the new model for the test by load.