The utility model discloses an anti-opening device for an electronic weighing instrument based on a reflection-type infrared tube, and relates to the technical field of electronic weighing. The interior of a front housing is provided with a reflection board, and the interior of a rear housing is provided with circuits. A baffle plate is disposed between the circuits. The voltage input end Vin of one circuit is connected with one end of a first resistor, and the other end of the first resistor is connected with the base electrode of a triode. The collector electrode of the triode is connected with one end of a second resistor, and the other end of the second resistor is connected with the VCC end of a power supply. The emitter electrode of the triode is connected with the anode of the transmitting tube of the infrared tube, and the cathode of the transmitting tube of the infrared tube is grounded. A side of the transmitting tube of the infrared tube is provided with the baffle plate, and a side of the baffle plate is provided with a receiving tube of the infrared tube. The cathode of the receiving tube of the infrared tube is grounded, and the anode of the receiving tube of the infrared tube is connected with an analog-digital convertor and one end of a third resistor. The other end of the third resistor is connected with the VCC end of the power supply. The device provided by the utility model can prevent an electronic remote-control device from being added through opening the electronic weighing instrument.