A DC-DC converter with constant power loads (CPLs) is a type of strongly nonlinear system. CPLs have the characteristic of negative incremental impedance, which may cause system instability during disturbances if the system is not properly controlled. Additionally, parameter uncertainty renders the control problem of nonlinear systems more complex and difficult. In this paper, a feedback linearization adaptive control strategy is proposed to improve the stability of a buck converter with CPLs. Feedback linearization is adopted based on the inverse system method to linearize the large signal average model of the buck converter with CPLs, and a pseudo-linear system is obtained. Then, a model reference adaptive control technology is applied to design a controller for the pseudo-linear system. Finally, compared with PID control, simulation and experimental results show that the proposed control strategy can achieve faster start-up without overshoots and stronger robustness in restraining resistive loads and CPL disturbances.