Abstract: In the study, we used Capsicum annuum(Long-jiao NO. 2, bred by Gansu Academy of Agricultural Science) as the experimental material to examine the effects of GA₃ application on growth, yield and quality of greenhouse vegetable C. annuum under the cultivation conditions of organic compound substrate. The results showed that compared with control(water), 200 and 250 mg·L^-1 GA₃ significantly increased the plant growth and dry weight accumulation, decreased the rates of flower and fruit abscissions, and increased fruit length, diameter, peel thickness, single fruit weight and yield, but no significant differences were observed between the two concentrations. Compared with control, 200 mg·L^-1 GA₃ significantly increased the plant height, dry weight accumulation, single fruit weight and yield by 11.8%, 22.5%, 16.1% and 7.6%, respectively. Moreover, 250 mg·L^-1 GA₃ significantly improved the quality of Capsicum annuum, and the Vc, soluble protein, soluble sugar were significantly increased by 19.7% and 22.6%, 18.4% and 14.8%, 15.0% and 14.9%, respectively. Spraying GA₃ also significantly improved the concentrations of abscisic acid (ABA) and indole acetic acid (IAA) in fruit, but had no significant effect on the concentrations of zeatins (ZR) during the fruit accumulation period. The results suggested that three times foliar application of 200 mg·L^-1 GA₃ can significantly promote the growth, increase yield and improve the quality of fruits of C. annuum from economy angle.