The crop intercropping basing on biodiversity effect mechanism is a hotspot of nutrient utilization, disease resistant,allelopathy and information exchange. In this paper, field experiment and pot culture were conducted to study the effects of flue-cured tobacco and sweet clover (Melilotus officinalis lam.) intercropping on soil nutrient contents. The results showed that no significant difference of the contents of available nitrogen and available P was found between the treatment of intercropping and single cropping, but in the middle or late stage of flue-cured tobacco growth, the content of available K increased in the intercropping treatment, which might contribute to the balance of soil nutrients.