The invention provides a method and device for controlling low-temperature heating start of an air conditioner and the air conditioner. The method comprises the flowing steps: acquiring an ambient temperature; when the ambient temperature is less than a set temperature, sending a first start command to a fan of an outdoor unit to control the fan to start and run at the highest speed; after the third duration, sending a second start command to a compressor to control the compressor to start; after the fifth duration, turning on an electronic expansion valve of the outdoor unit. The method for controlling low-temperature heating start of the air conditioner can rapidly establish the system superheat degree under the premise of ensuring low oil discharge of the system, improve the heat exchange effect, enable the compressor to heat quickly, reduce the oil discharge amount, ensure the reliability of the system and realize rapid heating of the air conditioner during low-temperature heatingstart.