Abstract: To find new plant growth regulators with high activity, the intermediate 2-amino-N-[3-(dimethylamino) propyl] benzamide was synthesized by using isatoic anhydride and DMAPA as the raw material. Phenyl isocyanate was added to the target compound N- [3- (dimethylamino) propyl]- 2- (3- phenylureido) benzamide. The structure was confirmed by elemental analysis and 1H NMR. Then, the efficacy was tested on wheat, apple and tomato. The results showed that in the wheat experiment, when the target compound was at a low concentration of 25 μg/mL, the germination promotion rate reached 32.6% and the high concentration had an inhibition effect. At 12.5 μg/mL, the main root promotion rate reached 36.3%, and the activity was better than that of the control DA- 6 and clear water, the field yield increased by 17.3% ; in the apple field experiment, the VC content increased by 35.0%, the soluble sugar content increased by 5.87%, and the single fruit yield increased by 25.2%, which was better than that of the control compound diphenyl urea; in the tomato field experiment, at 50 μg/mL, the number of fruits per plant was 12 and the increase rate reached 35.3%, which was better than that of the control of clear water. The research indicates that the target compound has high biological activity, and provides references for the synthesis and activity study of new plant growth regulators.