An electric control box for an outdoor unit of an air conditioner, comprising: a box body (100, 130); and a mounting plate arranged in the box body (100, 130), the mounting plate being provided with a first fan and a plurality of electronic components at a mounting side of the mounting plate, wherein: the first fan is configured to form first heat dissipation airflow flowing along a first heat dissipation path, wherein the first heat dissipation airflow being diverted by an inner wall of the box body (100, 130) to form second heat dissipation airflow flowing along a second heat dissipation path; the plurality of electronic components are distributed over the first heat dissipation path and the second heat dissipation path, the first heat dissipation path and the second heat dissipation path being located at the mounting side of the mounting plate; and further comprising a heat exchanger, the heat exchanger being a microchannel heat exchanger comprising at least two groups of microchannels, the at least two groups of microchannels including a plurality of first microchannels configured to allow a first refrigerant flow to flow through and a plurality of second microchannels configured to allow a second refrigerant flow to flow through, such that the second refrigerant flow is configured to absorb heat from the first refrigerant flow to subcool the first refrigerant flow, or the first refrigerant flow is configured to absorb heat from the second refrigerant flow to subcool the second refrigerant flow. a box body (100, 130); and a mounting plate arranged in the box body (100, 130), the mounting plate being provided with a first fan and a plurality of electronic components at a mounting side of the mounting plate, wherein: the first fan is configured to form first heat dissipation airflow flowing along a first heat dissipation path, wherein the first heat dissipation airflow being diverted by an inner wall of the box body (100, 130) to form second heat dissipation airflow flowing along a second heat dissipation path; the plurality of electronic components are distributed over the first heat dissipation path and the second heat dissipation path, the first heat dissipation path and the second heat dissipation path being located at the mounting side of the mounting plate; and further comprising a heat exchanger, the heat exchanger being a microchannel heat exchanger comprising at least two groups of microchannels, the at least two groups of microchannels including a plurality of first microchannels configured to allow a first refrigerant flow to flow through and a plurality of second microchannels configured to allow a second refrigerant flow to flow through, such that the second refrigerant flow is configured to absorb heat from the first refrigerant flow to subcool the first refrigerant flow, or the first refrigerant flow is configured to absorb heat from the second refrigerant flow to subcool the second refrigerant flow. the first fan is configured to form first heat dissipation airflow flowing along a first heat dissipation path, wherein the first heat dissipation airflow being diverted by an inner wall of the box body (100, 130) to form second heat dissipation airflow flowing along a second heat dissipation path; the plurality of electronic components are distributed over the first heat dissipation path and the second heat dissipation path, the first heat dissipation path and the second heat dissipation path being located at the mounting side of the mounting plate; and further comprising a heat exchanger, the heat exchanger being a microchannel heat exchanger comprising at least two groups of microchannels, the at least two groups of microchannels including a plurality of first microchannels configured to allow a first refrigerant flow to flow through and a plurality of second microchannels configured to allow a second refrigerant flow to flow through, such that the second refrigerant flow is configured to absorb heat from the first refrigerant flow to subcool the first refrigerant flow, or the first refrigerant flow is configured to absorb heat from the second refrigerant flow to subcool the second refrigerant flow.