Stable volume discharge of gas mixture is the foundation for discharge pumped gas laser, and preionization is one of effective solutions to stable volume discharge. The design of preionization pins of discharge-initiated pulsed HF laser was introduced, and preionization effects were evaluated by numerical simulation and experimental investigation. The simulation results show that the preionization electron density is about 109/cm3 in discharge area. The experimental results show that the output energy of laser with preionization is several times higher than that of without preionization in lower working voltage for SF6-H2 mixture, and for SF6-C2H6 mixture, the output energy of laser increases from 200 mJ to 297 mJ with preionization and the charging voltage of 20 kV, which is about 50% higher than that of without preionization. The simulation and experimental results show that preionization has effects on controlling and maintaining volume discharge and improving the uniformity of discharge.