Contact characteristics between soil and structure are related to soil types，degree of compaction，water content，etc. In order to study the contact characteristics between typical clays of Zhuzhou and concrete structure，9 soil samples of different water content and compaction degree are designed， and 4 different normal stress are applied to each type of soil samples with 50 kPa，100 kPa，200 kPa and 400 kPa for improved direct shear tests. The results show that the shear strength of the contact surface is larger with the density increscent，when the water content is larger，it is decreased with water content. The interface cohesion increases firstly with the water content increasing and after that rapidly decreases，it reaches the peak in plastic limit water content.