Abstract: To evaluate the applicability of AHC (agro-hydrological & chemical and crop systems simulator) model and explore the suitable irrigation amount for peanut (Arachis hypogaea) under mulched drip irrigation in the semi-arid areas of northwestern Liaoning Province, based on the two-year field experimental data of peanut in 2016 and 2017, the model parameters were firstly chosen for global sensitivity analysis. Then, module parameters of soil moisture and crop growth were calibrated and validated. Finally, AHC model was used to analyze the responses of peanut yield and water use efficiency (WUE) to different irrigation amounts. The results showed that the two extremely sensitive parameters of the model were saturated hydraulic conductivity in the first and second layers of soil. Root mean square error (RMSE) and mean relative error (MRE) between simulated and measured values of soil water content ranged from 0.02 to 0.03 cm³·cm^-3 and 1.5% to 2.3%, respectively. The RMSE and MRE of leaf area index and plant height were 0.3-0.6, 4.2-4.5 cm, and 5.0%-8.9%, 5.2%-6.8%, respectively. The MRE of peanut yield and water consumption were both within 5%, indicating that the model was suitable for simulating soil moisture and peanut growth in the northwest Liaoning Province. With the increases of irrigation amounts, peanut yield increased and water use efficiency decreased. Considering both peanut yield and WUE, we recommend that the optimal mulched drip irrigation amounts for peanut in the semi-arid areas of Northwestern Liaoning in test year (normal year) was 80-97 mm.