The application relates to an air conditioner heating control method, a controller and an air conditioner, and belongs to the air conditioner heating technology field. The air conditioner heating control method includes: acquiring weather parameters, wherein the weather parameters comprise temperature and humidity; confirming if normal heating running is needed or defrosting heating running is needed according to the weather parameters; and performing heating running control according to a confirmed result, wherein under the normal heating running, all coolant output by a compressor flows towards an indoor heat exchanger, and under the defrosting heating running, a part of the coolant flows into the indoor heat exchanger, the other part of the coolant flows towards a part, confirmed to perform defrosting, of heat exchange units in an outdoor heat exchanger, and the other heat exchange units in the outdoor heat exchanger are in a normal work state. The air conditioner heating control method can achieve adaptive continuous heating control by using the weather parameters, facilitates grasp of switching time of the normal heating running and the defrosting heating running well, and then facilitates improvement of heating effect and improvement of comfort experience of users.