For the purpose to make a small volume,high frequency,high power and narrow pulse laser driver,we designed a thyristor switch by using high power transistor with positive feedback,and would apply it to high-frequency pulse laser ranging and narrow pulse laser emission circuit.The laser reverse breakdown is suppressed by using the clamping diode laser.Through theoretical analysis for RLC circuit,the transistor switch circuit and thyristor device,SCR circuit was designed,and by analyzing principle of the discharge circuit,the whole driving circuit is simulated with SPICE program.Practical board was made.The peak current is 12 A and pulse width was 8 ns.