The invention relates to a control method and system for a daylight hothouse roller blind machine based on light and temperature coupling. The method comprises that a threshold of the illumination intensity is set according to the demanded illumination quantity of a hothouse plant and the growth phase of the plant, the illumination intensity and temperature of the outdoor environment as well as the temperature in the hothouse is detected, a central processor controls start of the roller blind machine in a light and temperature joint control logic algorithm, if the outdoor illumination intensity is greater than the set threshold, the light and temperature joint control logic requirement is met, the central processor emits an instruction to automatically control the roller blind machine, a central control chamber can monitor the environment factor, and multiple hothouses can be controlled manually via a 485 bus. The method and system support functions including illumination intensity sensing, real time monitoring, cluster control and automatic roller blind machine control, and are characterized by low cost, simple operation, wide application range, and safe operation.