An air conditioner indoor unit is provided. The air conditioner indoor unit includes: a base module, having a base part which is arranged with a fan motor; a heat exchange module having a heat exchanger and a connection pipeline for connecting the heat exchanger to an air conditioner outdoor unit; the heat exchanger and the connection pipeline are arranged in such a way that in a mounted state, the heat exchanger and the connection pipeline are entirely located at a front side of the base module; an air and water duct module having an air duct assembly; the air duct assembly is suitable to be entirely disassembled from the base part without disassembling the fan motor in the base part. During mounting, pre-assembly is first performed and then general assembly is performed; in such manner, the time needed to assemble the whole unit may be reduced.