The distributed optical fiber sensing technology is applied to the physical similarity model test of hard roof conditions in steep seam. By arranging the sensing optical fiber along the coal seam dip and laying the pressure sensor along the coal seam floor in the model, the deformation field and stress field in the model are monitored in real time, and the strain distribution and evolution characteristics of steep seam roof are analyzed with numerical simulation. The research shows that the stress value in the upper part of the working face is smaller than that in the lower and middle parts, and the stress value in the middle part is the largest. With the advance of the working face, the stress of the goaf floor is gradually released and the stress value is continuously reduced. The stress of the coal seam floor under the boundary pillars on both sides of the goaf is gradually increased, and the stress recovery degree of the middle and lower goaf floor is significantly higher than that of the upper floor; The optical fiber strain curve arranged along the dip of the coal seam is distributed in three sections, with two front and rear strain wave peaks and the corresponding middle wave valley of the goaf. Among them, the front wave peak is much higher than the rear wave peak; The deformation degree of the upper and middle roof of the working face is greater than that of the lower roof. The numerical simulation is consistent with the optical fiber detection results, which show that the deformation of the upper and middle roof is significantly greater than that of the lower. The research makes up for the shortage of monitoring means of physical similarity model test.