An embodiment of the invention provides a solar greenhouse illumination intensity control method and a solar greenhouse illumination intensity control system. The solar greenhouse illumination intensity control method comprises the steps of: determining an opening degree of roller shutters according to illumination intensity required in a greenhouse by utilizing a first correspondence between theillumination intensity in the greenhouse and the opening degree of the roller shutters on a lighting surface of the greenhouse; determining a geometric position of a roller shutter machine relative tothe greenhouse by utilizing a second correspondence between the opening degree of the roller shutter and the geometric position of the roller shutter machine, driving the roller shutter, relative tothe greenhouse; and controlling the roller shutter machine to act to the geometric position thereof relative to the greenhouse, so as to realize the control over illumination intensity in the greenhouse. According to the solar greenhouse illumination intensity control method and the solar greenhouse illumination intensity control system, the opening degree of the roller shutters is determined according to the illumination intensity required in the greenhouse, then the geometric position of the roller shutter machine relative to the greenhouse is determined according to the opening degree of the roller shutters, further the roller shutter machine is driven to act according to the geometric position, thereby realizing the real-time and quantitative control of illumination intensity in the greenhouse.