To improve the design of nature-like and technical fish passage, we propose a pool structure for a hydropower plant based on the target fish species requirements, and analyse the plane and 3-D flow pattern in pools by numerical simulation and physical model test. Result shows that by adding contraction section, side baffle block and strip bottom sills in nature-like and technical fish passage pools, the flow field in pools can be divided into different layers in longitudinal direction and different zones in horizontal direction to meet the requirements of different fish species with varying swimming performance. The proposed pool structure has advantages in velocity control and species selectivity compared with traditional nature-like and technical fish passage, and has practical application value.