During the software evolution, existing features may be adversely affected by new changes, which is well known as regression errors. Maintaining a high-quality test suite is helpful to prevent regression errors, whereas it heavily depends on developers. Continuously augmenting the existing test suite based on the new changes can assist developers in investigating the impact of these new changes. And by comparing the executions of the generated test case on two versions, existing techniques are able to detect some common errors. However, the requirements and oracles on the new changes with existing program behaviors are missing. In addition, the new changes may introduce new bugs when they are not sufficiently examined with other unchanged code, which finally fails to meet developers' real intentions on changes. In this paper, we propose the notion of evolutionary conflict checking to validate new changes. By extracting developers' intention reflected by new changes and transforming the linear evolutionary process into one three-way merge, we detect conflicts between existing behaviors and new changes. Our experimental results indicate that evolutionary conflict checking is able to be applied for guaranteeing software quality after changes.