A mixing nozzle includes a first connector, a second connector, a first channel and a second channel, where a first end of the first channel is connected to the first connector, and a second end of the first channel is provided with a spraying opening in communication with the first channel; a first end of the second channel is connected to the second connector, and a second end of the second channel is in through connection with the first channel; the first connector is configured to introduce a first fluid into the first channel, and the second connector is configured to introduce a second fluid into the second channel; and a length of the second channel is less than a length of the first channel.