Φ50mm hybrid motor test system and regression-rate measuring method were established in this paper. The basic composition of MA/HTPB/paraffin solid fuel was determined by consideration of performance, regression rate and density. To increase regression rate of solid fuels in hybrid motor, the action of combustion modifiers on the regression rates and performance of the solid fuels were investigated.The results showed that it is feasible to measure the regression rate of solid fuels by the Φ50mm hybrid teste...