Most traditional single-legged hopping robots use state-based control algorithms in height control. Position sensor is used in these algorithms, which results in the complexity of mechanics and control systems. To simplify the system, a control algorithm based on time event is proposed, which only uses ground-touch switch. A dynamics model considering pneumatic features is developed, the characteristics of the control algorithm are analyzed through simulation, and its effectiveness is verified with a prototype robot. The simulation and experiment results show that the robot using the control method based on time event not only can ensure the same stable margin and convergence speed, but also has flexible adjustment ability of hopping height and a simple system structure compared with algorithms based on state event.