Abstract: Ni-P alloy particles were synthesized by pulse discharge, and then their microstructure and effect on the thermal decomposition of ammonium perchlorate (AP) were studied. The results show that amorphous Ni-P alloy particles are composed of aggregates. The chord counts increase with increasing discharge voltage, leading to the reduction in diameter of Ni-P particles. The sizes of particles prepared at discharge voltages of 700, 900 and 1 100 V are 350 to 500, 250 to 400 and 150 to 300 nm, respectively. Ni-P alloy particles are beneficial to the thermal decomposition of AP at both low and high temperatures. In comparison with pure AP, Ni-P particles result in a decrease of the first (low temperature decomposition) and second exothermic (high temperature decomposition) peak temperature, and the decrease ranges are within 12℃ and about 53℃, respectively. The first exothermic peak is intensified with a reduction in size of Ni-P particles, but the second exothermic peak becomes weakened. In addition, the mass loss of low-temperature decomposition increases from 15.97% for pure AP to 42.78% for the mixture of AP and Ni-P particles, while the mass loss of high-temperature decomposition decreases from 81.62% to 47.58% and the end of high temperature decomposition is reduced by a range of 26 to 43℃.