Following the study on effects of different root temperature treatments on growth and stomata of tomato plants under high temperature in summer, the influence of different root temperature treatments on microstructure of tomato leaves was studied in depth in this paper. The tomato plants were cultured with circulating nutrient solutions. Under three different root temperature treatments [（23±1）, （28±1）, （33±1）℃], the microstructure of tomato leaves were observed and measured with paraffin section method. The results showed that with the increase of root temperature, the thickness, palisade tissue thickness, spongy tissue thickness of tomato leaves all decreased, but the epidermis thickness and palisade tissue thickness to spongy tissue thickness ratio increased. Therefore, increased root temperature led to drought stress to tomato plants, and in order to adapt to the hot and drought environment, tomato plants changed their structural characteristics.
