A communication circuit for indoor and outdoor units of an air conditioner, comprising: an outdoor unit sending module, connected with an outdoor unit sending end, wherein the outdoor unit sending module is switched on when the outdoor unit sending end is input with a high level, and the outdoor unit sending module is switched off when the outdoor unit sending end is input with a low level; an outdoor unit receiving module, connected with the outdoor unit sending module, and connected with an outdoor unit receiving end, wherein the outdoor unit receiving end outputs a high level signal 1 when the outdoor unit receiving module is switched on, and the outdoor unit receiving end outputs a low level signal 0 when the outdoor unit receiving module is switched off; an indoor unit receiving module, connected with the outdoor unit sending module, and connected with an indoor unit receiving end, wherein the indoor unit receiving end outputs a high level signal 1 when the indoor unit receiving module is switched on, and the indoor unit receiving end outputs a low level signal 0 when the indoor unit receiving module is switched off; an indoor unit sending module, connected with the indoor unit receiving module, and connected with an indoor unit sending end, wherein the indoor unit sending module is switched on when the indoor unit sending end is input with a high level, and the indoor unit sending module is switched off when the indoor unit sending end is input with a low level; a weak electricity grounding end connected with the indoor unit sending module; and a voltage regulation rectifying circuit, connected with the outdoor unit receiving module through a first connecting wire and connected with a main control board of an indoor unit, wherein the voltage regulation rectifying circuit, the outdoor unit receiving module, the outdoor unit sending module, the indoor unit receiving module, the indoor unit sending module and the weak electricity grounding end are sequentially connected in series to form a loop; and the voltage regulation rectifying circuit is configured to convert alternating current of the main control board of the indoor unit into direct current and supply electricity to the loop. an outdoor unit sending module, connected with an outdoor unit sending end, wherein the outdoor unit sending module is switched on when the outdoor unit sending end is input with a high level, and the outdoor unit sending module is switched off when the outdoor unit sending end is input with a low level; an outdoor unit receiving module, connected with the outdoor unit sending module, and connected with an outdoor unit receiving end, wherein the outdoor unit receiving end outputs a high level signal 1 when the outdoor unit receiving module is switched on, and the outdoor unit receiving end outputs a low level signal 0 when the outdoor unit receiving module is switched off; an indoor unit receiving module, connected with the outdoor unit sending module, and connected with an indoor unit receiving end, wherein the indoor unit receiving end outputs a high level signal 1 when the indoor unit receiving module is switched on, and the indoor unit receiving end outputs a low level signal 0 when the indoor unit receiving module is switched off; an indoor unit sending module, connected with the indoor unit receiving module, and connected with an indoor unit sending end, wherein the indoor unit sending module is switched on when the indoor unit sending end is input with a high level, and the indoor unit sending module is switched off when the indoor unit sending end is input with a low level; a weak electricity grounding end connected with the indoor unit sending module; and a voltage regulation rectifying circuit, connected with the outdoor unit receiving module through a first connecting wire and connected with a main control board of an indoor unit, wherein the voltage regulation rectifying circuit, the outdoor unit receiving module, the outdoor unit sending module, the indoor unit receiving module, the indoor unit sending module and the weak electricity grounding end are sequentially connected in series to form a loop; and the voltage regulation rectifying circuit is configured to convert alternating current of the main control board of the indoor unit into direct current and supply electricity to the loop.