This paper presents a modeling and transition algorithm of a novel wall-climbing robot with biped-wheel hybrid mechanism. In order to realize robot transitions between inclined surfaces, the robot’s locomotion gait is analyzed and a locomotion gait planning model based on Finite State Machine (FSM) is established. Moreover a transition algorithm between inclined surfaces is proposed based on multi-sensors data fusions and logical reasoning networks. The results of simulations and experiments show that the model and algorithm are valid and can be applied for the wall-climbing robot’s transition between the concave surfaces.