Abstract. Based on the redefined flow rate and flow pressure, the forward and backward state equations of long-stroke valve-controlled asymmetrical cylinder system are set up, in which the general mistakes in building up the flow rate equation are avoided. Then the simulation model in MATLAB/Simulink is established. Adopting the conditional-executive subsystem blocks, joint simulation with different models at two directions is realized by taking into account the continuity problems in positioning reversal. The subsystem of introduced equivalent volume function helps to show the effects of piston working position to valve-controlled cylinder system. Furthermore, with this simulation model, dynamic performance analysis of long-stroke valve-controlled asymmetrical cylinder system including some nonlinear factors becomes convenient.