In view of the fact that some difficulties exist in automatic and depthset sampling and monitoring for water, a new sampling system is developed. Firstly, the future sampler design ingredients are analyzed. Then the sampling system structure and operating principles are introduced in detail. A model machine is designed and several experiments have been carried on. The results indicate that this sampling system can perform automatic sampling effectively and efficiently; it could sample water as deep as 30m, and the depth error is less than 0.5m; water parameters such as temperature, pH and electrical conductivity (EC) can be measured on-site and the accuracy is 0.1∘C, 0.01 and 1μS/cm respectively. Besides, the sampler can reduce volatile organic components loss effectively and is also suitable to collect water sample for inorganic component analysis.