Abstract: The development process of post-arc sheath of vacuum circuit breaker is studied with the plasma fluid dynamics model applied.The drift diffusion equation of electron,ion density and average electron energy and coupling electric field Poisson equation is computed,the collision reaction between particles is introduced to simulate and analyze the spatial distribution,density distribution and potential distribution of electrons and ions in the post-arc dielectric recovery and sheath development stage.Moreover,control varieties is used to study the effects of different initial conditions on sheath development,the results show that:when other parameters remain unchanged,both the TRV slope and the axial length of the gap are positively correlated with the sheath development speed,the initial plasma density and post-arc metal vapor pressure are both negatively correlated with the sheath development speed.