The invention provides a communication device for a while-drilling stratum evaluation and geological guidance system. A measure while drilling (MWD) instrument end antenna and an MWD instrument end wireless conversion module are mounted in a non-magnetic drill collar together with an MWD instrument, and the MWD instrument end wireless conversion module converts MWD wired transmitted signals into low-frequency electromagnetic wave signals to be transmitted outwards through the non-magnetic drill collar, and meanwhile receives transmitting signals from other logging while drilling (LWD) instrument ends; and LWD instrument end antennas and LWD instrument end wireless conversion modules are encapsulated in heads of the LWD instrument ends together, signals transmitted by the MWD instrument arereceived, and meanwhile data and commands of LWD instruments are converted into low-frequency electromagnetic wave signals to be sent to the MWD instrument through the non-magnetic drill collar. Cascade connection can be conducted under the condition of the various instruments, the flexibility of instrument matching is improved, and unreliability and potential safety hazards of wire connection and slip ring type connection are eliminated.