Abstract: Time system plays an important role in modern space flight and normal weapon test shooting range. A novel decoder method is proposed that the real-time property of decoder is improved by FPGA and the precision is high. According to the signal feature of IRIG-B code, a new decoding scheme is put forward. The values in registers are preset by pulse-width modulation waveform and the IRIG-B code and shift register is compared. Then the code is identification and the time information can be resolved. The second pulse signal is triggered by shifting comparison with 111111110011111111 according to the starting marks information characteristics and 1pps signal is produced. It is simulated with ModelSim and is implemented on Xilinx's XC3S1000 chips. The trigger error of a single second pulse signal is less than 20 ns. Experiments prove that the proposed method has high precision, simple and practical, high efficiency, improve the decoding accuracy and strong anti-jamming.