The invention relates to the technical field of air conditioning control, in particular to an air conditioner defrosting control method and device. The air conditioner defrosting control method comprises the steps that S0, an air conditioner enters a defrosting mode; S1, defrosting is conducted by selecting a to-be-defrosted heat exchange branch from a plurality of heat exchange branches connected in parallel, the defrosted heat exchange branch communicates with a refrigerant pipeline of an air conditioner, and the rest of the heat exchange branches are disconnected with the refrigerant pipeline; S2, the actual pressure of the defrosted heat exchange branch is obtained; S3, the actual pressure of the defrosted heat exchange branch is compared to the preset pressure of the heat exchange branch, if the actual pressure of the defrosted heat exchange branch is higher than the preset pressure of the heat exchange branch, defrosting is completed, and the step S4 is carried out, and otherwise, the step S2 is conducted; S4, whether a to-be-defrosted heat exchange branch exists is judged, if yes, the process returns to step S1, and if defrosting of all the to-be-defrosted heat exchange branches is completed, the step S5 is conducted; and S5, the defrosting mode of the air conditioner is stopped. Defrosting is thorough, and the defrosting speed is high.