The invention relates to an accurate drift fault detection method and system of a temperature sensor, and an air conditioner. The method comprises: a temperature value detected by each of a plurality of temperature sensors in a same temperature environment is obtained; and the temperature sensor with a difference between the temperature value detected by the temperature sensor and an average value of temperature values detected by all temperature sensors larger than a set value is determined as one with an accurate drift fault. The number of the temperature sensors is larger than or equal to 3. According to the invention, a temperature sensor with an accurate drift fault can be determined precisely.