A telescopic tool pen with an illumination device comprises: a tube; a pen head inserted in one end of the tube; a telescopic pipe inserted in the other end of the tube, a lamp holder installed on the mounting seat of the telescopic pipe, a lampshade installed on the lamp holder for encapsulating the LED (light emitting diode), a magnetic member disposed in the mounting recess of the lampshade, a battery assembly arranged between the lamp holder and the telescopic pipe, and an actuator disposed in the telescopic pip. After the telescopic pipe extends out, the actuator will be withdrawn into the telescopic tube, and the spring will push the battery assembly into electrical contact with the ring of the telescopic pipe, thus turning on the LED, thus turning on the LED. When the tool pen is used to attract an accessory lost in the hole, the led can illuminate the location of the accessory, allowing the user to attract the accessory with the annular magnetic member very conveniently.