Abstract: In order to study the photosynthetic characteristics and root growth of tomato seedlings under non-uniform salt stress，the experiment adopted a split-root hydroponic system，and 3 salinity levels were conducted in the experiment including no salt stress（0），moderate salt stress（0.4%），severe salt stress（0.6%）. Each level divided into 6 treatments in accordance with the non-uniform and uniform salt stress of left and right root system，T1（0，0）as the control group，T2（0.1%，0.3%），T3（0.2%，0.2%），T4（0.1%，0.5%），T5（0.2%，0.4%），T6（0.3%，0.3%）. Photosynthetic indices，biomass，Na+ and K+ content and root growth parameters were measured under various treatments. The results showed that：（1）With the aggravation of salt stress，the content of Na+ in leaves increased，and the content of K+，photosynthetic index，biomass and root growth index decreased in turn；（2）Compared with uniform stress，Na+ content in leaves decreased significantly（P < 0.05），the stomatal conductance（Gs）was not significantly different from that under the uniform stress，but the net photosynthetic rate（Pn）and transpiration rate（Tr）increased. Compared with T3 treatment，the Pn，Tr increased by 4.88% and 3.83%，respectively. Under T4 treatment，the Pn，Tr of leaves increased by 13.51% and 8.25% respectively compared with T6，and the Pn of leaves under T5 treatment increased by 7.83% compared with T6，Tr increased not significantly；（3）The total root length，root surface area，root volume and total dry weight of both sides of roots increased under non-uniform stress when the centration is certain. The study indicated that non-uniform stress could improve the salt tolerance of tomato，which provided a theoretical basis for the growth of tomato in saline-alkali soil.

Key words: tomato, salt stress, non-uniform, uniform, split-root, hydroponics, total salt concentration