Abstract: The changes of sugar content，sucrose metabolism related enzyme activities and mineral elements in tomato fruits at different developmental stages were studied. Red fruit tomato‘Davis’(Dv) and pink fruit tomato‘Rolla’(La) were used as scions，and tomato‘Anta-T’(At) and‘Midako’(Md) were used as rootstocks. Regulation of the content of fructose，glucose and sucrose by scion and rootstock in tomato fruits at different developmental stages were found，and there was a significant interaction between scion and rootstock. At 30 d after flowering，sucrose content in fruit of Dv/At was 8.06% higher than that of Dv/Md，but there was no significant difference between La/At and La/Md. Meanwhile fructose content (16.44 mg • g-1 FW) in Dv/Md was 20.66% lower than Dv/Dv at 110 d after flowering，but there was no significant difference between La/Md and La/La. The difference of sugar content in tomato fruit with different grafting combinations was closely related to the activity of sucrose metabolic enzyme. The difference of sugar content in the early stage of fruit development of grafted tomato was mainly regulated the activity of acid invertase (AI) by scion in fruit. The difference in sugar content at late development stage was mainly due to the influence of rootstock on the activity of sucrose phosphate synthetase (SPS) and neutral invertase (NI). At the same time，nitrogen (N)，phosphorus (P)，potassium (K)，calcium (Ca)，magnesium (Mg) and iron (Fe) in tomato fruits with different grafting combinations were significantly different. Curve estimation analysis showed that N and P content in fruit were significantly negatively correlated with invertase activity (AI and NI)，fructose and glucose，and significantly positively correlated with sucrose content. Therefore，in the process of tomato grafting to promote the quality and yield of tomato，the management of nitrogen and phosphorus nutrients after grafting should be coordinated with the absorption characteristics of rootstocks，so as to avoid the decrease of sugar content and flavor of tomato fruits caused by increase of nitrogen and phosphorus absorption.

Key words: tomato, rootstock, scion, sugar accumulation, nitrogen and phosphorus