This paper presents design of altitude controller with disturbance compensation for an indoor blimp robot and its realization. Due to hardware restrictions, the altitude control behavior of blimp is modeled as a switched system with fixed time delay accompanying with uncertain bounded disturbances. HOMD differentiator is used as an observer for vertical velocity and switching signal estimation. Then a predictor-based controller is conceived, in order to compensate the perturbation, the method for disturbance evaluation is designed. Control scheme is implemented by Matlab Simulink, finally, the performance of blimp improved altitude controller is verified in experiments.