Voltage sourced converter-high voltage direct current (VSC-HVDC) transmission has been widely applied all over the world owing to its unique advantages. Converter valve is the key equipment of VSCs, its losses are significant to the economically operation of VSC stations. Analysis and accurate measurement of the losses can make great contribution to efficiency optimization, devices selection and thermal design, etc. This paper investigates the losses measurement technology of power electronics equipment and surveys the academic research at home and abroad of the double pulse method, electrical method and thermal method for losses measurement. It comes up with three test schemes for measuring losses of VSC sub-modules respectively, the schemes include measuring method, test circuit design, equipment selection, software platform and its control method, test procedure, uncertainty and loss estimation method. In the physical test platform, tests based on three schemes are carried out, the uncertainty of tests results is analyzed. This paper provides reference for measuring losses of VSC sub-modules in practical projects.