Abstract: Stand age plays a crucial role in forest biomass estimation and carbon cycle modeling. Assessing the uncertainty of stand age prediction models and identifying the key driving factors in the modeling process have become major challenges in forestry research. In this study, we selected the Shaanxi-Gansu-Ningxia region of Northeast China as the research area and utilized multi-source datasets from the summer of 2019 to extract information on spectral, textural, climatic, water balance, and stand characteristics. By integrating the Random Forest (RF) model with Monte Carlo (MC) simulation, we constructed six regression models based on different combinations of features and evaluated the uncertainty of each model. Furthermore, we investigated the driving factors influencing stand age modeling by analyzing the effects of different types of features on age inversion. Model performance and accuracy were assessed using the root mean square error (RMSE), mean absolute error (MAE), and the coefficient of determination (R²), while the relative root mean square error (rRMSE) was employed to quantify model uncertainty. The results indicate that the scenarios with more obvious improvement in accuracy and effective reduction in uncertainty were Scenario 3 with the inclusion of climate and water balance information (RMSE = 25.54 yr, MAE = 18.03 yr, R² = 0.51, rRMSE = 19.17%) and Scenario 5 with the inclusion of stand characterization information (RMSE = 18.47 yr, MAE = 13.05 yr, R² = 0.74, rRMSE = 16.99%). Scenario 6, incorporating all feature types, achieved the highest accuracy (RMSE = 17.60 yr, MAE=12.06 yr, R²=0.77, rRMSE = 14.19%). In this study, elevation, minimum temperature, and diameter at breast height (DBH) emerged as the key drivers of stand-age modeling. The proposed method can be used to identify drivers and to quantify uncertainty in stand-age estimation, providing a useful reference for improving model accuracy and uncertainty assessment.