Abstract: As an important ecological land and natural resource, the quantity, type, spatial layout, and age structure of forestland have a significant impact on its functional performance. Linear spectral mixture model can avoid the influence of mixed pixels on spectral information, providing technical support for accurate and fast acquisition of regional forest information. Taking Zhangjiakou City as an example, based on linear spectral mixture model, combined with random forest classification algorithm and logistic model, this study used Landsat series remote sensing images to carry out fine forestland classification and forest age mapping. The results showed that: 1) The forestland in Zhangjiakou City could be divided into five types: evergreen coniferous forest, deciduous shrub forest, deciduous small-leaved forest, deciduous roadleaved forest, deciduous needle-leaf forest. The overall classification accuracy was 90.58%, the Kappa coefficient was 0.89, and the classification accuracy was high. In 2020, there were significant differences in the area occupied by various forestland types and their distribution in horizontal space. Among them, deciduous shrub forest had the widest distribution area in the study area, accounting for 31.25%. Deciduous roadleaved forest had the second largest distribution area, accounting for 3792.80 km². Deciduous needle-leaf forest had the smallest distribution area in the study area, accounting for only 480.32 km². 2) We used field sample point data, validation samples obtained from Google Earth high-resolution images to compare and validate the forest age classifications obtained in this study, and obtained that the average absolute error of the forest age in Zhangjiakou City mapping was within 2 years, and the deviations were all within 3 years, which indicated that the method of forest age mapping was more effective. The mapping results showed that the spatial distribution pattern of each age group in Zhangjiakou City in 2020 differed significantly. Forestland with an age of 20-30 years had the largest distribution area among age groups, with an area of 3704.75 km², while forestland with an age of ＞30 years had the smallest area among the five age groups, accounting for only 119.98 km². 3) As for different forestland types, their distribution areas showed a tendency of increasing and then decreasing with the increase of elevation and slope. Among them, the evergreen coniferous forest was primarily distributed at an elevation range of 1500-2 000 m. Deciduous shrub forest and deciduous needle-leaf forest were both concentrated within the elevation range of 1000-1500 m. Deciduous small-leaved forest and deciduous roadleaved forest were aggregated within the elevation ranges of 1000-1500 m and 1500-2 000 m. In terms of slope distribution, deciduous small-leaved forest predominantly grew with a gradient of 2-6°, while others were primarily concentrated on the gradients of 6-15° and 15-25°. As for different forest ages, the area of each age group reached the highest level in the elevation band of 1000-1500 m. The age groups of 5-10 years and 10-20 years had the largest distribution area in the slope zone of 15-25°, and the forest age of 20-30 years occupied the largest area in the slope zone of 6-15°. The area of each age group was smaller in the flat land with a slope of ＜2°. This study provided a visual basis for the spatial distribution and age structure of regional forestland, which was of great significance for optimizing forest resource allocation and promoting ecological sustainable construction.