Abstract: A universal intrinsic safe power cannot reliably supply for a long distance passive RFID reader card station because of the large load capacity and extreme pulse current. In view of this problem, through the analysis of the generation process of capacitive load electric spark, a high current, high stability and small volume intrinsical safety power supply based on the control of single chip microcomputer is developed by means of fast shutdown, load on-off detection, soft startup and segmental current limiting technology. The output voltage of this power supply is 12 V and the current is 1.8 A. It has been proved by experiments that this power supply can provide stable and reliable power supply for passive RFID reader substation.