By the analysis and comparison of self-designed and developed SQY-1 fixed-depth sampler for hydrological well about the performance characteristics and applicability, the paper discussed its working principle and operation method. The fixed-depth sampler effectively solves the difficulties of water sample collection in the wells in composite aquifer with large water quality variation, accurately reflects the aquifer water quality in different buried depth of strata and is used in hydrogeology survey as a new practical sampling tool.