The invention relates to the field of 
rocket engines, in particular to a novel 
hydrogen peroxide multistage 
catalytic decomposition type 
gas generator, which comprises a first-stage 
hydrogen peroxide inlet, wherein a first-stage 
hydrogen peroxide silver mesh catalytic 
bed, a first-stage lattice structure, a second-stage 
hydrogen peroxide gas-
liquid injection disc, a second-stage downstream mixing cavity, a second-stage lattice structure, a third-stage 
hydrogen peroxide gas-
liquid injection disc, a third-stage downstream mixing cavity, a third-stage lattice structure and a generator outlet are sequentially arranged on the downstream of the first-stage 
hydrogen peroxide inlet, a second-stage hydrogen peroxide inlet is formed in the second-stage hydrogen peroxide gas-
liquid injection disc, and a third-stage hydrogen peroxide inlet is formed in the third-stage hydrogen peroxide gas-liquid injection disc. According to the 
gas generator, high-temperature and high-pressure gas with rated flow is generated through self-
decomposition reaction of multistage hydrogen peroxide, 
mechanical equipment such as a 
turbine and the like are pushed to do work, large-range adjustment of the flow of the 
gas generator is achieved through three-stage gas inlet, it is guaranteed that the 
working pressure is stable, and the 
power capability of the generator is improved.