A method and system for LED calibration is provided for a plurality of LED modules cascaded in a series. Each LED module includes a plurality of LEDs, a driver and a controller. The control signal from a calibration host is transmitted to all the modules to light all LEDs in the LED module. Through the controller of the LED module, the calibration data transmitted from the calibration host is stored in the memory inside the driver so that all the LEDs will emit light according to the calibration. The present invention improves the uniformity of the light emission and improves the module maintenance convenience.