The asymmetrical digital hydraulic cylinder with double thread pair structure is designed, and the working mechanism is analyzed. The digital cylinder model is built by AMESim, and the simulation of asymmetric digital cylinder that is controlled by the symmetric valve and theasymmetric valve is carried out respectively under noload and constant force load. The resultsprovethat, during reversing, the pressure jump can be eliminated by applyingthe asymmetric valve. Especially,when the cylinder extends under negative load, cavitation can be avoided by the asymmetric valve. It provides a useful attempt for the optimal design of the digital cylinder.