The workspace of the 4-HSPS/PRPUR macro/micro actuated parallel mechanism applied to a scanning electron microscope is analyzed. The 4-HSPS/PRPUR macro/micro actuated parallel mechanism is composed of a base and a moving platform connected by four HSPS branches and a middle PRPUR branch. It has three translational degrees of freedom and two rotational degrees of freedom about the X axis and Y axis. Because the macro actuation and micro actuation are integrated together in this mechanism, this paper analyzes the constant orientation workspace and the dexterous workspace of this mechanism. The analysis shows that this mechanism can move flexibly in large workspace and the link length of the middle branch has considerable influence on the shapes of the workspaces. On the analysis of the constant orientation and dexterous workspaces of this mechanism, it demonstrates that the mechanism is suitable for the work condition of smaller platform mount space, large workspace and higher positioning accuracy. This study provides a theoretical basis for the application of the 4-HSPS/PRPUR parallel mechanism.