A kind of intelligent tobacco quantitative hole application topdressing machine based on opposite-type infrared photoelectric sensor and microcontroller was designed. When the topdressing machine moved forward pulled by the engine, 20 pairs of opposite-type infrared photoelectric sensors of the sensor detection device accurately detected the central position and diameter of the tobacco plant, then the microcontroller determined the best topdressing point and controlled the duckbill to complete the automatic and quantitative hole application topdressing. The test results showed that the detection accuracy rate of sensor detection device reached to 99%, the topdressing accuracy reached to 97%, and the tobacco plant injury rate was less than 2%. 