A novel 3DOF parallel manipulator of pure rotation was introduced and structural design was addressed. The inverse kinematical solution of the mechanism and the general constraint conditions impacting on the workspace were analyzed. The workspace of manipulator was represented by using the area where the endpoint of unit normal vector of the moving platform was able to reach. Based on an actual dimension as an example, the workspace was shown by using graph method and the maximum rotation angle of the mechanism was calculated with the help of MATLAB. The impact of the critical factors on the workspace and the maximum rotation angle were analyzed. The result indicates that when the height is placed causing the initial rod length in the middle position, and the circum circle radius of the dynamic and the static platform are close, the mechanism has quite large workspace and rotation angle.