Abstract: A gauge transformation approach is used to resolve the Schrodinger equation for time-dependent quantum systems. We first make use of this method to solve the known model of spin 1/2 system in a rotation magnetic field. Second, we apply the approach to a laser-driven two-level system. We calculate the high-order approximation and nonadiabatic effects of the system, through this method of successive approximation we realize the transition of adiabatic solution to the strict solution.

Key words: gauge transformation, time-dependent quantum system, two-level system