Minimal change is a fundamental principle for modelling system dynamics. In this paper, we study the issue of minimal change for Computational Tree Logic (CTL) model update. We first consider five primitive updates which capture the basic update operations in the CTL model. Based on these primitive updates, we then define the minimal change criteria for CTL model update and develop formal algorithms that embed the underlying minimal change principle. We also present the well known microwave oven scenario to demonstrate our update algorithms. Our work presented in this paper can be viewed as the first formalization towards an integration of model checking and model updating for system modification.