To design a safe path planning for the manipulator is a key issue during the human worker and manipulator cooperation cell assembly. In this study, a cell assembly system involving human worker and manipulator is designed. According to the camera vision information, the locations of the human worker and the manipulator are calculated, and then the potential field is calculated based on the Artificial Potential Field (APF) method. In order to generate a semi-optimal safe path planning for the manipulator, a criterion is imported to evaluate the path and an Evolutionary Algorithm (EA) is adopted to adjust the parameters to meet this criterion. The effectiveness of these methods is finally confirmed through simulation experiments.