Abstract: The impact of noise AM jamming on starting probability of pseudo-random code phase modulation fuze (PRCPMF) was researched. The starting probability of the PRCPMF was deduced under noise AM jamming. Factors influencing the starting probability were discussed. The simulation results showed that the starting probability cloud be reduced by increasing the input jamming to signal ratio(JSR) of the receiver, and by minishing jamming bandwidth and improving noise effective modulation coefficient and noise quality factor, the starting probability cloud be improved by reasonably reducing the starting threshold level of the PRCPMF, and by increasing the code period and decreasing the code-element width and the Doppler frequency.