Preliminary site testing shows that Antarctic inland Dome A is likely to be the best astronomical observatory site on the ground, Chinese first Antarctic astronomical equipment CSTAR has been successfully run Dome A. Three Antarctic Schmidt Telescopes (AST3) is the next important Antarctic astronomical equipment, one of which will be mounted Dome A. In the year of 2010, and the three will be installed Dome A finally. Because of the very low temperature and saturation vapor pressure, and the temperature gradient changes fast near the ground layer at Dome A, the mirror is easy to be frosted, which is one of difficulties to AST3.Indium Tin Oxide (ITO)is an N-type semiconductor material, because it has few resistors, good light transmission, good weather resistance, small environmental impact, low cost, and it is easy for large area coating, so it is widely used in many fields. The mirror is heated by ITO that is coated on the surface of the mirror, the voltage on the ITO will be tuned by changing the output pulse width, and then the system achieves a closed-loop control. The difference between the mirror temperature and ambient temperature will be maintained in an ideal range, and this will not only ensure that the mirror surface will not get frosting, but to minimize the impact of mirror seeing to guarantee the image quality of the telescope. The experimental results show that the temperature control system can control the different temperature between the mirror surface and the ambient less than 2 degree in real time, which can improve the mirror’s working environment, and the overall effectiveness of the telescope’s observations.