A millimeter wave signal transmission integration device includes an antenna array module, a flexible substrate, a coaxial cable and a signal processing module. The antenna array module is used to transmit and receive millimeter wave signals, and convert millimeter wave signals to intermediate frequency (IF) signals or convert IF signals to millimeter wave signals. The flexible substrate is connected to the antenna array module, and is used to transmit/receive IF signals. The coaxial cable is connected to the flexible substrate and is used to transmit and receive IF signals. The signal processing module is connected to the coaxial cable and is used to transmit and receive IF signals. With the above configuration, the present invention achieves the effects of reduced occupied space of the millimeter wave signal transmission module and reduced attenuation of IF signals.