Abstract: To find out the solutions to the problems of clayey soil texture and blocked growth and development of flue-cured tobacco, the paddy soil with continuous cropping of flue-cured tobacco for five years in Yuxi, Yunnan Province was taken as the research object. The composition of soil grain size was changed by exogenous sand mixing. The composition of soil water-stable aggregates, physicochemical indexes, enzyme activities, nutrient absorption, and dry matter accumulation of flue-cured tobacco were studied, and the correlation was analyzed. The results showed that compared with the treatment without sand mixing, the sand content increased by 44.55% and 58.59% after sand mixing of 30% and 60% (p<0.05), respectively. The content of clay and silt decreased with the increase of sand mixing. After sand incorporation, the content of <0.25 mm particle size agglomerates significantly decreased and the content of large agglomerates increased, and the stability of soil agglomerates was 30% sand incorporation > 60% sand incorporation > no sand incorporation; Soil pH and catalase activity increased, organic matter, available potassium and other major nutrients decreased, and the activities of sucrase and acid phosphatase after 30% sand addition increased by 20.42% and 268.69%, compared with no sand addition. Pearson correlation analysis and redundancy analysis showed that the effect of soil mechanical composition on soil properties and nutrient accumulation was significant. Most of the growth indexes, soil pH, and catalase activity were positively correlated with sand content (p<0.01), and negatively correlated with clay and silt content (p<0.01). Soil aggregate stability was positively correlated with sand content. In summary, the proportion of 30% sand in paddy soil was appropriate in this experiment, which could significantly improve soil structure and quality, block soil acidification, enhance nutrient absorption, and promote tobacco plant growth.