In this paper, the heat and moisture balance of heating type heat pump drying system (HHPDS) is analyzed from the point of view of air conditioning. The ability that to effectively control the drying temperature and humidity is defined as the control capability. The relationship between the control capability and the drying temperature and humidity, the temperature and humidity of the environment and the amount of material is explained based on the principle of heat pump. Through the qualitative analysis of the influence of various factors, the conditions of determining the control ability of the HHPDS were obtained and it also pointed out the scope of judgment and the non judgment range. On the basis of theoretical analysis, the phenomenon, which the low temperature and high humidity is difficult to control in autumn is explained.