Abstract: At present, the conventional hydraulic reamer while drilling can only be installed at the top of the while-drilling tool of directional well and large-displacement circulation cannot be realized after the reaming. To deal with these problems, this paper developed the wireless signal based electric-control hydraulic reamer. In this novel reamer, the ball-activated ball seat assembly is replaced with the pressure transmission system and pulse generator assembly and electric control system assembly are installed, so that the instructions can be transmitted through drilling fluid pulse signals and drill pipe rotation signals to control blade’s extension and retraction. Then, the stress on the piston of pulse generator when the pressure transmission hole of the pressure transmission system is opened was calculated and analyzed. In addition, the erosion situations of the pressure transmission hole were analyzed using the fluid simulation software. The field test results show that the wireless signal based electric-control reamer is reasonable in design and can transmit the instructions successfully in three modes to extend and retract the blade normally. The research results provide the foundation for the further study on intelligent reamers.