Device of measuring formation resistivity of drill

The invention discloses a device of measuring formation resistivity of a drill. The device comprises a tool housing; an emitter disposed on the tool housing and used for generating electric signals and converting the electric signals into electromagnetic signals to be emitted to a formation; a receiver arranged on the tool housing, positioned at an axial place of the emitter and used for measuring amplitude and phase of the electromagnetic signals from the emitter; and an emission signal coupler coupled to the emitter and used for coupling part of electric signals of an antenna of the emitter and measuring amplitude and phase of the coupled electric signals. An amplitude and phase difference between the electromagnetic signals received by the receiver and the electric signals coupled by the emission signal coupler is utilized to calculate resistivity. The device of the invention helps to solve problems of measurement lag caused by a distance between a drill and a conventional propagation logging tool. The device is improved to be more practical.