The positive DC corona discharge process in SF6 gas is simulated using the hydrodynamical model from finite element simulation software COMSOL in this paper. The characteristics of space current pulse excited by corona discharge under different applied voltages, temperatures, and needle-plate gaps are investigated. The findings indicate that the discharge process can be categorized into three distinct stages: current rise, current fall, and current stabilization. The current rising stage results from the formation of electron avalanche; the current falling stage occurs due to a reduction in the number of electrons in the tip region, weakening ionization reactions and causing the positive ion cloud to move away from the needle electrode; at the current stabilizing stage, electron avalanche process is nearly completed and there is a slowdown in the drift rate of positive ion clouds away from the tip region. The rise and fall time of pulse current show a negative correlation with applied voltage and temperature but a positive correlation with needle-plate gap. Moreover, both peak and steady-state current exhibit direct correlation with applied voltage and temperature while inverse correlation with needle-plate gap.