Abstract: The efficiency testing for pump units in transporting system is the means judging its performances and/or a fundamental work in energy saving and consumption reducing. The subject whether the testing results are accurate or not and how to reduce the testing errors has not heen discussed so thoroughly in the past. Error analysis is a important measure to improve the accuracy of testing resits. Thus, based on the error theory, the error sources in the efficiency testing of pump unit are analyzed, and it is considered that the main error in efficiency testing of pump unit are induced by the measuring errors of outlet pressure and flow rate of pump, and input power of electric motor. The measures against errors are put forward, that is, improving the accuracy of pressure meter at outlet of pump and flowmeter; paying attention to high gravitational difference between the suction and discharge of pump while the outlet pressure is lower; measuring the transfer efficiency with the electrical energy gauge method.