This paper represents the design of a robot end effector which is supposed to be a tool of measuring the orientation accuracy and repeatability. The motivations and ideas of this testing tool are stated, firstly. Then, its structure parameters are specified and the testing accuracy is computed by mean of analyzing the manufacturing errors and structure stiffness which are measured and simulated by Carl Zeiss CMM and Abaqus, respectively. Moreover, the orientation accuracy and repeatability of Kunshan No.1 and KUKA L16 are tested in terms of ISO 9283 standard using this testing tool and API Tracker3. Finally, the results are analyzed and compared which show that the design of this testing end effector is competent with a high cost-effective ratio.