A device for mixing or multiplying frequency, comprising: a metal housing, comprising a box body and a cover buckled together to define a metal cavity; at least one frequency conversion unit, comprising: a microstrip line located in the metal cavity; and a channel structure comprising a radio frequency signal input channel, a local oscillator signal input channel and a signal output channel, the radio frequency signal input channel, the local oscillator signal input channel and the signal output channel pass through the metal housing and are coupled to the microstrip line respectively, wherein at least two of a plane where the radio frequency signal input channel is located, a plane where the local oscillator signal input channel is located and a plane where the signal output channel is located are not coplanar, wherein the signal output channel is led out perpendicularly to a plane where the microstrip line is located; wherein each of the radio frequency signal input channel and the local oscillator signal input channel is located in a plane in parallel to the plane where the microstrip line is located, characterized in that: each of the radio frequency signal input channel and the local oscillator signal input channel extends in a direction in parallel to a length direction of the microstrip line; and wherein each of the radio frequency signal input channel and the local oscillator signal input channel is coupled to the microstrip line through a turn. a metal housing, comprising a box body and a cover buckled together to define a metal cavity; at least one frequency conversion unit, comprising: a microstrip line located in the metal cavity; and a channel structure comprising a radio frequency signal input channel, a local oscillator signal input channel and a signal output channel, the radio frequency signal input channel, the local oscillator signal input channel and the signal output channel pass through the metal housing and are coupled to the microstrip line respectively, wherein at least two of a plane where the radio frequency signal input channel is located, a plane where the local oscillator signal input channel is located and a plane where the signal output channel is located are not coplanar, a microstrip line located in the metal cavity; and a channel structure comprising a radio frequency signal input channel, a local oscillator signal input channel and a signal output channel, the radio frequency signal input channel, the local oscillator signal input channel and the signal output channel pass through the metal housing and are coupled to the microstrip line respectively, wherein at least two of a plane where the radio frequency signal input channel is located, a plane where the local oscillator signal input channel is located and a plane where the signal output channel is located are not coplanar, wherein the signal output channel is led out perpendicularly to a plane where the microstrip line is located; wherein each of the radio frequency signal input channel and the local oscillator signal input channel is located in a plane in parallel to the plane where the microstrip line is located, characterized in that: each of the radio frequency signal input channel and the local oscillator signal input channel extends in a direction in parallel to a length direction of the microstrip line; and wherein each of the radio frequency signal input channel and the local oscillator signal input channel is coupled to the microstrip line through a turn.