The vertical slit fishway has the characteristics of simple partition type, good flow conditions of water, and clear mainstream position, making it suitable for fish migration in different water layers. It is currently the most widely used fish passage engineering. Under the same conditions of length to the width ratio, vertical seam position, and partition thickness of the pond, three types of fishway pond partition are preliminarily designed. Modeling software is used to build a mathematical model and numerically simulate the structure of the first type of fishway pool chamber. The numerical simulation process includes determining the model boundary conditions, meshing the model, inputting calculation parameters, and conducting solving calculations of model. The maximum flow velocity near the vertical joint of the 2-9 partition plate calculated by the mathematical model is compared with the water flow pattern of surface of the tank chamber with the maximum flow velocity near the vertical joint measured by the model experiment of physics and the water flow pattern of surface of the tank chamber, to verify the rationality of the optimization of the partition plate type and size in the mathematical model. The numerical simulation method is used to calculate three types of fishway tank structures, and the baffle type is optimized by analyzing the maximum flow velocity of the water along the main flow zone and trajectory of different tank structures, as well as the flow velocity at different depths near the vertical seam of the 5th baffle. A 1:5 scale local physical model test is conducted on the determined optimized partition type, which involves measuring the flow velocity with different vertical joints in different depths; a model test of physics is conducted on a scale of 1:20 for the determined optimized partition type, with measurements of the flow velocity at the vertical joint and the water depth along the way. The test results show that when the water depth at the outlet of the fishway is not less than the inlet water depth, i.e. in operating conditions 1 and 4, the flow velocity near the vertical joints of each partition is less than the design flow velocity of 1.2 m/s. Under operating conditions 1 and 4, where the water depth at the outlet of the fishway is equal to or greater than the inlet, and the flow velocity near the vertical joints of a partition at one's inlets is relatively high. The maximum current speed in these conditions is 1.319 meters per second, while for operating condition 3, it is 1.561 meters per second, with both maximum values more than 1.2 meters per second. This paper recommends operating the fishway under conditions 1 and 4. At the same time, the hydraulic properties of fishway under water are examined, and it is suggested that a 4-meter per second impact flow velocity value should be used to improve structural strength in the baffle and guide plate of this multi-stage water tank located at the head of that channel. [ABSTRACT FROM AUTHOR]