The invention discloses an accelerated on-line test system for the service life of an LED, and relates to an LED test system. The system comprises an aging device, a spectrum collection device, an electric test device, and a computer control processing module. The aging device is provided with a constant temperature controller and an aging constant current source. The spectrum collection device is provided with at least one optical path, a cosine collector, a testing sampling clamping tool, a sixteen-way optical multiplexer, and a spectrometer. The electric test device is provided with an electric matrix switch and a testing source meter. The computer control processing module comprises a computer control part and a computer processing part. A PID heater is employed for the direct temperature control of an LED heat sink, thereby not only enabling the system to achieve miniaturization and temperature control to be more accurate and stable, but also saving a large amount of energy. Moreover, the heater is provided with a thermal insulation device, thereby preventing high temperature from affecting testing equipment. An on-line testing result is more continuous, and an error caused by the inconsistence of testing conditions is avoided. Testing parameters are complete. The service life can be predicted more accurately in a short time through the combination of a physical model and a mathematic model.