Theoretical analysis and simulation are carried out to analyze the motion of a pneumatically actuated leg. A control strategy using pressure difference between upper and lower cylinder chambers to make the leg get off ground in touch-ground period is proposed, which can minimize the energy loss. An energy regulation based control strategy used in flight period is proposed to enhance the stability of the leg system. Influences on the hopping height and center of mass are analyzed when the position of the cylinder piston is changed during flight period, which enriches the methods of hopping height regulation. Test-bed for the pneumatically actuated leg is constructed, and the experimental results match well with the simulation results.