Abstract: Objective to research the photosynthetic physiology, yield and quality changes of peanut under chemical regulation. In this experiment, it was a comparative study on chemical regulation of mepiquat chloride, chlormequat chloride and paclobutrazol. The results showed that, three plant growth regulators decreased plant height and transpiration rate of leaf, increased stem diameter, the number of effective branch and pods, chlorophyll content and photosynthetic rate in peanut leaf, finally achieved the aim of increasing the yield of peanut and improving the quality of peanut. In comparison, the chemical regulation of paclobutrazol on increasing chlorophyll content, yield and crude protein content and decreasing the transpiration rate of peanut were best, and yield and crude protein content of paclobutrazol treatment were 9.0% and 7.8% more than control. The net photosynthetic rate in peanut leaves of mepiquat chloride treatments was the highest, it was 25% more than controlled. The chlormequat chloride was best for improving the linoleic acid content of peanut seed, its linoleic acid content was 6.4% more than control. In conclusion, the chemical regulating effect of paclobutrazol on pod yield, quality and photosynthetic physiology of peanut was the best, followed by the mepiquat chloride.