This paper presents the first-order time-varying difference equation, the characteristic odel. Only two parameters are involved in the equation. The adaptive iterative earning control method is suggested to deal with the characteristic-model based control problem, here the learning identification algorithms with a forgetting factor are introduced to stimate the time-varying unknowns. For PMLSM servo-systems, in this paper, an adaptive terative learning control scheme is proposed based on the LQ optimal control strategy. Numerical nd expereiment results are presented to demonstrate effectiveness of the control scheme.