The invention discloses a Reynolds experiment instrument, which aims to solve the problems that according to an existing experiment device, the water consumption is large, the appearance is easy to corrode, the movement is inflexible, and a colored liquid pollutes an experiment guide tube. The Reynolds experiment instrument comprises a pressure stabilizing overflow water tank, a separating funnel, an experiment guide tube, a rotor flowmeter, a lower water tank, a water pump, an experiment table, a flow adjustment valve and a thermometer. The pressure stabilizing overflow water tank is located on the top end of the experiment table; the thermometer is arranged in the pressure stabilizing overflow water tank; the lower water tank is arranged on the bottom end of the experiment table; the water pump is arranged at the left lower corner of the lower water tank; the separating funnel is arranged in a tank bottom circular through hole of a tank bottom in the pressure stabilizing overflow water tank; a drain pipe at the lower end of the separating funnel is inserted into a pipe port at the upper end of the experiment guide tube; the lower end of the experiment guide tube is connected with a pipeline on the upper end of the flow adjustment valve; the lower end of the flow adjustment valve is connected with the lower end of the rotor flowmeter through a first section of rubber pipe; the upper end of the rotor flowmeter is connected with the lower water tank through a second section of rubber pipe; the water pump is connected with the pressure stabilizing overflow water tank through a third section of rubber pipe.