For one class of fractional-order chaotic system with systematic uncertainties and external disturbances, firstly, fractional calculus is applied into sliding controller, and a sliding surface with a fractional integral term is designed. As to the systematic uncertainties and external disturbances of the system, based on the fractional Lyapunov stability theorem and adaptive control method, a sliding controller accompanied by fractional adaptive laws is then proposed to achieve the synchronization of fractionalorder chaotic systems. Moreover, the bounds of uncertainty and disturbance in the corresponding systems are identified. It should be pointed out that the fractional Lyapunov theorems and functions introduced in the stability analysis of the fractionalorder chaotic systems can be applied to many other control methods for fractionalorder nonlinear systems. Finally, numerical examples are given to verify the effectiveness and feasibility of the proposed control method.