The utility model provides a support seat assembly for testing drive axle assemblies. The support seat assembly comprises a fixed frame; a set of transverse adjustment bracket capable of moving along the fixed frame along the horizontal direction is arranged at the upper end of the fixed frame and comprises a transverse adjustment bottom plate and a transverse adjustment stand column fixed at one end of the transverse adjustment bottom plate; the transverse adjustment stand column is provided with an up and down adjustment bracket capable of moving up and down along the transverse adjustment stand column; the transverse adjustment bottom plate is provided with a telescopic support rod; the upper end of the telescopic support rod is fixedly connected with the up and down adjustment bracket; and two sets of longitudinal adjustment bottom feet are respectively and fixedly connected with the two sides of the fixed frame. The support seat assembly can be used for conveniently adjusting the positions of the different drive axle assemblies and a test stand, so that the demands of the drive axle assemblies with different plate spring distances and heights can be met, and an input end of the drive axle assembly and a power output end of the test stand can reach the coaxality and the equal height with certain accuracy; and the support seat assembly is high in universality, convenient to adjust and accurate in test data, and effectively saves the test cost.