Adding modules such as MCU, camera, the gear motor and stepper motor to the traditional Michelsoninterferometer to improve it, the improved Michelson interferometer is used to measure the refractive index ofethanol solution at different temperatures. Based on Open CV image recognition technology, the number offringes is identified and the relationship is obtained by the least squares fitting.Experimental results show thatthe improved device is easy to use and accurate in measurement. After data fitting, the relationship between thetemperature and refractive index of ethanol solution is obtained , providing referenee data for seienee, industryand other fields.