Abstract: A thyristor switched three-stage magnetic pulse compressor for ArF excimer laser was studied. This all solid state pulse power module can replace the commonly used thyratron switch. The thyristor and magnetic core used were both domestic products. The rise time of a high voltage pulse was compressed from 5 μs to 150 ns. Output energy of 0.35 J to 0.68 J and voltage of 10 kV to 14 kV were obtained. The energy transfer efficiency of the three-stage magnetic pulse compressor was 35%. At last, the reason for low efficiency was discussed and several measures were provided to improve the energy transfer efficiency.