Code change which introduces risk in software quality is associated with regression test case prioritization. It is an important topic that evaluates the code change impact on regression test case prioritization, which plays a significant role in software quality assurance. This study analyzes the relationship between regression test case and code change from a test coverage and coupling perspective based on the test case prioritization evaluating model, and presents a new code change impact metric model which introduces both the dominant and recessive impact level. Experiments indicate that, the quantitative metric results of code change impact to regression test cases prioritization computed by this model are comprehensive and objective, and could provide effective support for regression test case prioritization evaluation.