Abstract: Tending thinning and unthinning trees with good growth are selected as the research objects to explore the effect of thinning on the wood tissue ratio and tracheid morphology characteristics of Pinus tabulaeformis in the mountainous area of northern Hebei. The results show that the transverse section of P. tabulaeformis mainly consists of tracheids, wood rays and resin channels. On the radial section, the cross-field pattern between the ray parenchyma cells and the axial tracheids is window-pane type, and a few are pine-type; on the cut surface of the string, there are single-row and spindle-shaped wooden rays, containing dark resin. The microstructure characteristics of thinning and unthinning P. tabulaeformis are basically the same. The average values of the length, width, aspect ratio and wall-to-cavity ratio of the thinning and unthinning P. tabulaeformis tracheids were 3439 μm and 3323 μm, 46.57 μm and 44.83 μm, 73.20 and 73.51, 0.42 and 0.41; the length of the thinning P. tabulaeformis tracheids, width, aspect ratio and wall-to-cavity ratio are all larger than those of unthinning. In terms of tissue ratio, there is no significant difference between thinning and unthinning P. tabulaeformis.