The cylindrical permanent magnet is the core part of the permanent-magnet seed-metering device, it can absorb single magnetic powder coated seed. The first, the magnetic induction intensity model of any point in the cylindrical permanent magnet external was established based on the equivalent current model of permanent magnet. The second, the mathematical formula was derived using the Biot-Savart law and the superposition principle of magnetic field. Then its magnetic induction intensity was calculated by multiple numerical integration function of MATLAB, and the characteristics and distribution were obtained. On this basis, the simulation and analysis of the permanent magnet with height 7mm and diameter 2mm was finished. The results showed that the closer the field point was to the permanent magnet end face, the stronger the magnetic induction intensity was, and the magnetic induction intensity at the edge of end face was stronger than at the center. So the diameter of the cylindrical permanent magnet should be less than magnetic powder coated seed, meanwhile, the air gap between the permanent magnet end face and the magnetic powder coated seed should be smaller as much as possible or the magnetic powder coated seed directly contacted with the permanent magnet end face.