The invention discloses a unit defrosting control method and device. The unit defrosting control method comprises the steps that running parameters of a unit direct contact sensor are obtained; according to the obtained running parameters, whether a unit is located in a state representing frosting of a unit heat exchanger or not is determined through the obtained running parameters; and when the unit is judged to be located in the state representing frosting of the unit heat exchanger, a defrosting mode is started to conduct defrosting treatment on the heat exchanger. According to the unit defrosting control method and device, by adoption of the direct contact sensor, whether defrosting is conducted or not is directly determined through the running parameters of the direct contact sensor, and the unit defrosting control method is faster than a method relying on a indirect mode before, is shorter in consumed time and capable of timely finding and starting the defrosting mode when frost is not frozen or not firmly frozen so that running of an air conditioner can be more stable and reliable, improves the running property and product quality of the unit in winter, saves energy and protects the environment.