The invention discloses an air conditioner with the function of a water heater, and mainly includes a compressor, an inside evaporator, a condenser and a water can with a heater converting pipe inside. The invention is characterized in that the outlet of the compressor is connected at one end of the upper part of the heat converting pipe through a gas intake pipe. And the other end of the lower part of the heat converting pipe is connected with one end of a liquid storage which can through a gas outtake pipe, the other end of the liquid storage can is connected with the inlet of the condenserthrough the arrangement of an electronic inflation valve. The outlet of the compressor is also connected with the inlet of the condenser through the arrangement of a defrosting electromagnetic valve.The outlet of the condenser is provided with two pipelines, wherein, one of the pipelines is connected with the inlet of the inside evaporator through a capillary, and the outlet of the inside evaporator is connected with a gas-liquid separator through a pipeline; the other pipeline of the condenser outlet is directly connected with the gas-liquid separator through a pipeline provided with an airconditioner/water heater switch valve. The air intake opening of the compressor is connected with the gas-liquid separator through a pipeline. The invention achieves good result in energy saving.