Conventional mobile robots can only overcome obstacles of limited height while hybrid mobile robots, which combine the wheeled motion and jumping motion, have better crossing obstacle capabilities. The excellent jumping abilities of hopping robots result from their core parts - the hopping actuators. In this paper, we propose a kind of hopping actuator powered by gas fuels, and explain its inner structure and basic working principles. Then the factors that affect jumping performance of the hopping actuator are analysed by orthogonal experimental design, and the result shows that the inner radius of the piston and initial charging pressure are the top two main influencing factors. Finally outdoor experiments are conducted to validate the correctness and applicability of the orthogonal array analysis.