Aiming at the simultaneous influence of magnetic field and temperature on the magnetic fluid current sensor, optical current sensor based on magnetic fluid is studied and the experimental system of temperature characteristics of the sensor is built. The results show that in the range of 26 ℃~74 ℃, the thermal lens effect of magnetic fluid causes a temperature gradient, and the temperature of the constant temperature water bath increases the Brownian motion of the magnetic, therefore, the transmittance of the magnetic fluid optical current sensor decreases as the temperature of the constant temperature water bath increases.