PID control is used widely in hydraulic servo control system. The PID control parameters are very important to performance of hydraulic servo control system and how to find rapidly the optimum values of PID control parameters is a very difficult problem. Based on Matlab/simulink software and taking the IATE standards of the optimization design as objective function, a global search optimization method with the modified Biogeography-Based optimization (MBBO) was applied for the optimization of the three parameters of PID controller of electric-hydraulic servo system of parallel platform. Biogeography-based optimization (BBO) is a novel evolutionary algorithm that is based on the mathematical models of biogeography. Biogeography is the study of the geographical distribution of biological organisms. In the BBO model, problem solutions are represented as islands, and the sharing of features between solutions is represented as immigration and emigration between the islands. In this paper, a modified version of the BBO is proposed to improve its convergence. The MBBO is used to deal with the PID Controller tuning. Simulation results show that the proposed parameter optimum method is an effective tuning strategy and has good performance compared with adopted NN network optimization method. (5 pages)