Abstract: In order to achieve a rational state of vegetative and reproductive growth of Cucurbita maxima in plastic greenhouse, the authors tried to use different chemical substances to induce female flowers and control vegetative growth. India pumpkin variety‘Yong’an NO.2’was used as the experimental material, and different chemical substances were applied in pumpkin seedling stage. The results showed that the treatment of Zenggualing and ethephon could dramatically decrease the first female flower node, promote flowering and increase the number of female flowers in the pumpkin seedling stage, 100 mg/L ethephon had the best effect of promoting female flowers. However, paclobutrazol, chlormequat and Zenggualing inhibited the vegetative growth of pumpkin, 500 mg/L paclobutrazol and 200 mg/L chlormequat had the best effect. Meanwhile, Zenggualing (15 g per bag added 3 kg water) had a dual action of promoting female flowers and inhibiting vegetative growth. The results indicated that these four kinds of chemical substances used in the seedling stage of Cucurbita maxima could induce female flowers and control vegetative growth, and be widely applied in agricultural production.