In order to solve the technical problem of I-V curve tester in terms of quantity transmission and traceability, the author has realized the online measurement of the open circuit voltage (Voc) and short circuit current (Isc) parameters of I-V curve tester through the research and development of solar cell’s Voc and Isc measurement method and technology, thus completing the system online calibration of the I-V curve tester. The relative indication errors of Voc and Isc online calibration are 0.45% and 0.20% respectively. This work meets the demand of traceability of related equipment in photovoltaic industry, and provides the technical support for the healthy development of the industry.