The utility model discloses a heating dehydrating unit for sub - case of transformer station side, including the power, evenly lay the heat band no longer than 70 DEG C at terminal box inner wall and operating temperature for gather the temperature and humidity sensor of temperature and humidity in the terminal box, and according to the controlling means in temperature and humidity controlled heating area in the terminal box, give controlling means through temperature and humidity sensor detection terminal incasement temperature and humidity and transmission, controlling means according to the start -up in temperature and humidity controlled heating area with stop. The utility model provides a tradition heating dehydrating unit heat distribution of the sub - case of transformer station side inhomogeneous, easily cause operating environment humidity overproof's in the terminal box problem, the tradition heating dehydrating unit heat of having solved the sub - case of transformer station side simultaneously is too high, and equipment is ageing in the accelerating chamber, easily causes the problem of moving maintainer and scalding.