Underwater glider is a new type of autonomous underwater vehicle driven by gravity. In order to study the relationship between the motion parameters and control variable of the underwater glider, solve the fluctuation problem of pitching angle and attack angle in the process of attitude changing, simulation via the software Mat lab is performed based on the kinematic equations of underwater glider in vertical plane. The results show that the longer the cycle of bary center adjusting, the smaller the fluctuating extent of the pitching angle. It seems that this fluctuation of underwater glider is not affected by the variation of buoyancy adjusting, and the fluctuation of attack angle may be affected by the time center location difference between these two adjusting cycles.