Applying controllable pendulum to indicating vertical is a new method which can be used for autonomous navigation. There are some studies on the method and it puts forward the existing problems. In this paper, it carries on the preliminary study on drawbacks that it exists steady-state error in controllable pendulum, and designs a new control scheme combined direct control with indirect control while there is step perturbation. Then it designs the corresponding control law by using observer with state feedback and decoupling control. It makes software simulation by Matlab and the results show that the controllable pendulum can be controlled well to indicate vertical by using the designed control scheme and control law when it exists step perturbation.