Handheld fixed-torque electric wrench

The invention relates to a wrench, in particular to a handheld fixed-torque electric wrench which comprises a handle, wherein the front end of the handle is fixedly connected with a shell; the internal rear part of the shell is provided with a motor; the output shaft of the motor is fixedly connected with a first-stage central wheel of a planetary reducer; a final-stage central wheel of the planetary reducer is connected with the rear end of a torque output shaft through a final-stage planetary wheel; the front end of the torque output shaft penetrates through a bearing seat in a lining at the front end of the shell to extend out of the shell; the front end of the torque output shaft is provided with a square shaft; a torque sensor is arranged outside the torque output shaft in the shell; the front end of the torque sensor is connected with the lining; the rear end of the torque sensor is connected with a final-stage inner gear ring of the planetary reducer through an inner gear; the handle is provided with a start button and a positive and negative rotation switch; and the start button, the positive and negative rotation switch, the motor and the torque sensor are respectively connected with a controller through cables. The wrench of the invention has simple structure, is convenient to use, and lightens the working labor intensity and improves the working efficiency on the premise of ensuring tightening accuracy.