Vuilleumier gas-coupling pulse tube cryocooler (VM-PT) is a novel kind of cryocooler capable of attaining liquid helium temperature. For investigating on the complex mechanism of gas distribution between two stages

a numerical model of VM-PT cryocooler was built by using Sage software. The influence of the operating frequency

the average pressure

the length of capillary tube and the filling length of Er3Ni on the distribution characteristics of mass flow were studied respectively. The results showed that those four parameters would change the gas distribution between two stages and then influence the coldest temperature of VM-PT cryocooler. By weighing the cooling capacity of working gas and the losses of regenerator

those parameters had its optimal value for the performance of cryocooler. Then

an experimental bench was built to verify the results of simulation. By optimizing the parameters of capillary tube and the filling method of a cold regenerator

a no-load temperature of 3.86 K was obtained in the experiment and the cooling capacity at 4.2 K was demonstrated to be about 10 mW.