The invention discloses a millimeter wave radar chip capable of being cascaded. The millimeter wave radar chip includes a substrate, millimeter wave transmitting and receiving ports RF1 to RF4, four phase shifter units A, B, C and D, eight millimeter wave switch units S0-S7, power divider cascade adaptive interface units E and F, a millimeter wave voltage-controlled oscillator and frequency multiplication unit V, a millimeter wave mixer unit M, a mixed analog intermediate frequency signal interface unit I, a serial peripheral interface unit SPI, a millimeter wave voltage-controlled oscillatorunit Vt for receiving an external control signal to regulate and control the interior, and a radar chip power supply interface unit PWR. According to the invention, the cascading of the multiple radarchips is simple, and the cascading can be completed only through the adaptation of the cascading adapter interface of the power divider; the circuit is simple in structure, only transmitting waveforms generated by a phase-locked loop need to be transmitted to a main mode chip in a cascade system, intermediate frequency output by the main mode chip is transmitted to a post-stage ADC to be sampled,intermediate frequency output by a slave mode chip does not need to be transmitted to the post-stage ADC to be processed, and therefore post-stage processing is simple.