Aiming at the requirement of measuring hydrodynamic characteristics for low speed underwater vehicle,a small indoor low speed open water tunnel was designed which met the similar theoretical requirements.Fluent was used to calculate the velocity distribution of each cross section for the test section,and the cross section range that met the test conditions was selected.Finally,the test platform was built,and its flow field was calibrated.The result shows that the test steady section velocity reaches 2 m/s,meanwhile,the flow field is uniform and stable,and the range is larger than 200 mm×68 mm×300 mm,which conforms to the blocking rate is not more than 25%,the length of the test section is usually three times the length of the model.The correctness of the simulation results is verified and the expected test requirements for low velocity underwater vehicle model is met.This test system is suitable for experimental conditions：velocity is not more than 2 m/s,the model length is not more than 200 mm,and cross section area of flow direction is not more than 5 000 mm2.