The most difficult problem for High Test Peroxide (HTP), which is used in monopropellant thruster for satellite, is the catalyst bed design. According to literature, silver has the best catalytic performance for HTP, but its low melting point usually sinters the silver catalyst bed during decomposition processes. A superior catalyst bed design has to deal with the balance of the highest specific impulse produced and life-span of the active catalyst bed performance. The sintering effect always accompanies with the incomplete decomposition in cold start and oscillation in chamber pressure. Even more, it will induce flow instability in the supplying system. In this paper, we add some ceramic materials to increase the thermal resistance ability of catalyst bed, which names as composite silver catalyst. We design a HTP monopropellant thruster model for the test of the proposed catalyst; and discuss the factors influencing the decomposition processes and the deterioration of the catalyst bed. By anticipate packing, we can find an excellent result for the test of catalyst. No matter in cold start or hot fire, the C* efficiency in the catalyst is almost 100%. The Isp from cold start is 104.9 s; and Isp from hot fire is 114.9. The start transient is about 100ms and 50ms, which include the operation time of solenoid valve, from cold and hot fire. It is a successful development for H2O2 monopropellant thruster.