The invention belongs to the field of millimeter-wave imaging, and provides a millimeter-wave imaging device. The millimeter-wave imaging device comprises a crystal oscillator, a power divider, a millimeter-wave receiving and sending unit, a local-oscillator signal processing unit, a second frequency mixer and an image processing module; the power divider is used for conducting power distribution on an oscillation signal generated by the crystal oscillator and outputting a clock trigger signal and a local-oscillator signal; the local-oscillator signal processing unit is used for processing the local-oscillator signal and outputting a second local-oscillator signal; the millimeter-wave receiving and sending unit is used for processing an echo signal reflected by a to-be-measured object and outputting a first intermediate frequency signal; the second frequency mixer is used for conducting frequency mixing on the second local-oscillator signal and the first intermediate frequency signal and outputting a second intermediate frequency signal; the image processing module is used for processing the second intermediate frequency signal and imaging the to-be-measured object. As the crystal oscillator serves as a clock trigger source of the millimeter-wave receiving and sending unit and a local-oscillator signal source of the second frequency mixer at the same time, the local-oscillator signal source does not need to be additionally arranged, the circuit structure is simplified, and cost is reduced.