To solve the problems of convergence speed dependence on initial value and poor robustness of existing sliding mode control methods in uncertain nonlinear systems, a new global fixed-time sliding mode control strategy is proposed. Firstly, the designed fixed-time disturbance observer effectively eliminates the adverse effects of uncertain disturbances within the system. Then, a non-singular fast terminal sliding mode surface is utilized, which not only successfully overcomes the singularity problem, but also significantly enhances the system's robustness. In addition, it ensures that the convergence time is independent of the initial states of the system. Furthermore, an A-T (arctan-tanh) approaching law is designed by combining arctangent and hyperbolic tangent functions. Meanwhile, the stability of fixed-time perturbation observers and non-singular fast terminal sliding modes is rigorously proved applying the Lyapunov stability theory. Finally, the experimental results of the two-joint manipulator further verify that the proposed algorithm has good control effect.