Abstract: The current methods for designing the random vibration test load for complicated units, like the ESM and the AFM, can hardly satisfy the demand of load tailoring from the manufacturers of the units, because the prediction results always are too high to be acceptable compared with the practical load in some loading directions. Thus a modified random vibration test load design method, the DMM, is proposed in this paper, with the random excitation power spectral density as a fractional function with coefficients to be determined by the measured results of the overall root-mean-square of acceleration obtained from the satellite acoustic tests. The prediction precisions are compared among three design methods. It is shown that in contrast with the established methods, the modified method can reduce the prediction errors significantly and therefore a reasonable constraint can be set for the structure and mechanism optimization design of complicated spaceborne units.