To study the degradation law of overburden strength caused by mining height. Based on the reasonable determination of the mining height during the initial mining stage of Guojiawan 51208 working face, the variation of fracture density is used to measure the degradation of overlying rock strength caused by mining height. Theoretical and numerical analysis models of the degradation of overlying rock strength under different mining heights are established, and the influence of mining height on the stability of overlying rock is obtained by combining the parameters of the mining face. The results show that: (1) With the increase of mining height, the rotation angle becomes larger and the thickness of the rock layer loaded by the bearing layer gradually decreases, making the rock layer more prone to rotational deformation and instability. (2) When the advancing length of the working face is less than 50m, the maximum displacement of the overlying rock and the distribution of the plastic zone at the basic top are basically the same for mining heights of 2.5m and 4.0m; When the advancing length of the working face is ≥ 50m, the maximum displacement of the overlying rock at a mining height of 4.0m increases by more than 10% compared to 2.5m, and the plastic zone at the basic top increases significantly. (3) The advance support pressure increases with the increase of mining height, while the initial pressure step distance decreases with the increase of mining height. The initial pressure step distance for a mining height of 2.5m is around 70m. (4) The initial mining height of 2.5m is adopted, and the mining height is gradually adjusted to the actual coal thickness (4.0m) after the first pressing of the old roof, making the initial mining of the working face more efficient and safer. The above research results are expected to provide reference for the control of the roof in the initial mining of the working face.