In order to study the dynamic characteristics of direct drive pump\|controlled electro\|hydraulic servo system , the working principle of the system was analyzed, and the mathematical models of pump\|controlled system and valve\|controlled system were built to carry out theoretical analysis and comparative research of dynamic response. A servo drive system laboratory bench was set up taking AC servo motor and fixed displacement pump as the power source，on which both control systems performance can be tested. The numeral simulation and the experimental study of dynamic response for the experiment system were done. The result shows that the rise time of the pump\|controlled system is 8 times longer than that of the valve\|controlled system because of its low hydraulic natural frequency and slow dynamic response. On the basis of the research, the measures to improve the dynamic characteristics of such systems were put forward.