An air conditioner, comprising: a heat exchange loop for exchanging heat between indoors and outdoors, wherein a heat exchanger is provided in the heat exchange loop, and the heat exchanger has an upward flow path and a downward flow path; wherein the heat exchanger includes: flat tubes having provided therein a plurality of micro-channels and being used for circulating a refrigerant; a second header communicating with the flat tube in the downward flow path and being used for circulating the refrigerant; a third header communicating with the flat tube in the upward flow path and being used for circulating the refrigerant; and a connecting pipe communicating with the second header and the third header and being used for circulating the refrigerant; wherein, the second header includes: a cavity portion communicating with the connecting pipe and being used for circulating the refrigerant; a channel portion, an end of the channel portion communicating with the cavity portion, and another end of the channel portion communicating with the flat tube, the channel portion being used for circulating the refrigerant; and characterized in that, a flow disturbing portion provided in the cavity portion, the flow disturbing portion being used for disturbing a flow of the refrigerant in the cavity portion. a heat exchange loop for exchanging heat between indoors and outdoors, wherein a heat exchanger is provided in the heat exchange loop, and the heat exchanger has an upward flow path and a downward flow path; wherein the heat exchanger includes: flat tubes having provided therein a plurality of micro-channels and being used for circulating a refrigerant; a second header communicating with the flat tube in the downward flow path and being used for circulating the refrigerant; a third header communicating with the flat tube in the upward flow path and being used for circulating the refrigerant; and a connecting pipe communicating with the second header and the third header and being used for circulating the refrigerant; wherein, the second header includes: a cavity portion communicating with the connecting pipe and being used for circulating the refrigerant; a channel portion, an end of the channel portion communicating with the cavity portion, and another end of the channel portion communicating with the flat tube, the channel portion being used for circulating the refrigerant; and characterized in that, a flow disturbing portion provided in the cavity portion, the flow disturbing portion being used for disturbing a flow of the refrigerant in the cavity portion. flat tubes having provided therein a plurality of micro-channels and being used for circulating a refrigerant; a second header communicating with the flat tube in the downward flow path and being used for circulating the refrigerant; a third header communicating with the flat tube in the upward flow path and being used for circulating the refrigerant; and a connecting pipe communicating with the second header and the third header and being used for circulating the refrigerant; wherein, the second header includes: a cavity portion communicating with the connecting pipe and being used for circulating the refrigerant; a channel portion, an end of the channel portion communicating with the cavity portion, and another end of the channel portion communicating with the flat tube, the channel portion being used for circulating the refrigerant; and characterized in that, a flow disturbing portion provided in the cavity portion, the flow disturbing portion being used for disturbing a flow of the refrigerant in the cavity portion. a cavity portion communicating with the connecting pipe and being used for circulating the refrigerant; a channel portion, an end of the channel portion communicating with the cavity portion, and another end of the channel portion communicating with the flat tube, the channel portion being used for circulating the refrigerant; and characterized in that, a flow disturbing portion provided in the cavity portion, the flow disturbing portion being used for disturbing a flow of the refrigerant in the cavity portion.