The invention belongs to the technical field of plant lighting, and particularly relates to a photometry method for evaluating the influence of artificial lighting on the photosynthesis of garden plants. Through switching between a light quantum system, a plant photometry system and a photometry system, illumination values corresponding to the PPFs of light compensation points and light saturation points of the plants are worked out to determine an illumination reference range of planting lighting, and the influence of artificial lighting on the plants is evaluated through the illumination photometry method; according to a light distribution curve of lamps, an equal-illumination three-dimensional curved surface of the light compensation points and light saturation points of the plants is worked out to obtain the safety lighting distance and the minimum lighting distance of the plants. The method has important reference value in evaluating the influence of artificial lighting on the photosynthesis of the garden plants. The safety lighting distance and the minimum lighting distance recommended by the method can be used for instructing a plant worker or a lighting designer to select lamps and reasonably arrange the lamps, and the method has importance significance in creating green lighting and providing a harmonious light environment.