In this study, tomato scion variety ‘Yingfen No. 8’and stock variety‘Zhenai No. 1’were used as test materials. 100 mg·L^-1 CCC was foliar sprayed on tomato scion and stock when 6 and 12 days before grafting, respectively. The growth indexes of tomato seedlings, the contents of plant hormones in the grafted union were measured, and the effect of CCC on the process of grafting formation was monitored. The results showed that: (1) CCC significantly inhibited scion and stock seedlings growth, reduced the plant height by 33.30% and 33.96%, respectively. The aboveground fresh weight of scion and stock seedlings and dry weight of stock were reduced. (2) At 12 and 48 h after grafting, CCC decreased the contents of GA₁₅ and GA₈, increased the contents of GA₃₄ and GA₃ at 48 and 72 h after grafting; At 12, 48 and 72 h after grafting, CCC increased the contents of TRP, MEIAA, TRA, IAA, tZOG and iP9G. (3) 48-168 h after grafting, CCC increased the fuchsin absorption content and mean fluorescence intensity of vascular bundles in the grafted union; 72 h after grafting, the grafted union treatment by CCC was connected with xylem vessel elements; 96-120 h after grafting, the reconnection of xylem and phloem of the grafted union was basically completed treatment by CCC, the parenchyma cells of callus filled the gap of the grafted union, which was earlier than control. (4) 20 days after grafting, CCC increased SPAD value of scion leaves and root activity of stock. The results showed that foliar spraying CCC before grafting could effective promote the reconnection of vascular bundles and the growth and development of grafted seedlings.