Abstract: In order to analyze key position of deformation of trapezoidal metal support, the mechanical models of trapezoidal metal support are established based on universal pressure theory and principle of force law. And then, the analytical solutions of key position of deformation of trapezoidal metal support are deduced. Furthermore, the strength of key position of deformation of different types of mine steel brackets is analyzed. The effects of the inclination of shed column and the internal friction angle of rock on the key position are discussed. It is studied that the key part deformation of different types of mine trapezoidal steel beams are all at mid-span cross-section of canopy beams, and there are not relevant to the loads, bottom width of caving arch and the internal friction angle of rock. The key position of shed column relates to the size of roadway section, bottom width of caving arch, the dip angle of shed column and the internal friction angle of rock, and it lies between 0.55 m to 0.63 m from roadway floor. With the increase of the angle of the shed column, the key part of the column deformation is farther away from the roadway floor, and with the increase of internal friction angle, the key part of the deformation of the shed column is closer to the bottom of the roadway.