In view of the influence of nocturnal light note on plant photosynthetic rhythm，the response of garden plant photosynthetic rhythm to nocturnal light was studied.Using the research methods of landscape botany and architectural optics，the experiment was carried out with three kinds of light intensity of five kinds of LED light sources commonly used at night，and the response of photosynthetic rhythm of garden plants to light was monitored.These data include net photosynthetic rate，stomatal conductance，transpiration rate，etc.The results showed that the photosynthetic rhythm of garden plants had a positive response to the light at night.The value of photosynthetic rhythm at night was higher than that before artificial light，and the value of photosynthetic rhythm in daytime was increasing gradually.The stronger the light intensity at night，the more positive the response of photosynthetic rhythm.The response of photosynthetic rhythm of garden plants was promoted by the light of blue violet light，yellow light and white light spectrum.The conclusion is that the response trend of photosynthetic rhythm of garden plants to nighttime light and the influence of nighttime light on urban environment can be grasped.This conclusion can be used to control the damage of night light to urban environment.