Abstract: Maize stover is one of the by-products or agricultural residues during production, particularly with a substantial yield and wide distribution. There is a significant energy conversion potential in the context of renewable and clean energy. The rational utilization of the maize stover can alleviate the energy shortages and environmental concerns. For instance, the improper stover disposal (such as open burning) can release a large amount of greenhouse gas. However, the compact microstructure of the maize stover has posed notable challenges to the effective energy conversion, due primarily to the complex cross-linking of lignin, cellulose, and hemicellulose. Some pretreatments, such as ensiling, have been employed to enhance the biodegradation and anaerobic digestion efficiency. However, there is still a lack of information on their impact on the digestibility of the raw materials. Particularly, it is often required to break down the rigid lignocellulosic matrix. This study aimed to improve the anaerobic digestion and methane production efficiency of ensiled maize stover. The chemical pretreatments were evaluated to clarify the influence mechanisms of the NaOH, γ-Valerolactone (GVL)/NaOH, alkaline hydrogen peroxide, and Fenton's reagent on the methanogenic performance, anaerobic digestion stability, and reaction of the ensiled maize stover. Both the energy conversion efficiency and economic benefits were also compared under different pretreatments from the perspectives of physicochemical properties, elemental composition, and microstructure. The results showed that the cellulose content of the pretreated NG1 group increased from 41.35% to 69.21%, and the hemicellulose content increased from 8.76% to 17.77%, whereas the lignin content decreased from 14.77% to 5.56% (81.76% removal rate), compared with the feedstock (CK group). The microstructure showed that the lignocellulosic structure of the NG1 group was severely damaged, and the total crystallinity index was significantly reduced (P<0.05). Moreover, the NG1 group maintained stable pH, optimal NH₄⁺-N levels, and low IA (intermediate alkalinity)/PA (partial alkalinity) values (<0.6) during digestion, indicating the excellent system stability. Furthermore, the cumulative methane production of the NG1 group was as high as 375.17 mL/g (using volatile solids), which was 26.08% higher than that of the CK group; The maximum methane production rate was 25.43% higher than that of the CK group; And the lag period (λ value = 0.94 d) was significantly (P<0.05) lower than those of the rest pretreated groups (1.49~2.37 d). In contrast, the alkaline hydrogen peroxide (AH group) and Fenton's reagent pretreatment (FE group) resulted in the inhibition of the methanogenic performance, due to the excessive degradation of energy-containing components in the ensiled stover and limited lignin removal. The economic gain analysis showed that the net gain of the NG1 group was 968.20 yuan/t, which was 13.32% higher than that of the CK group, indicating the best economic benefit. Therefore, the technical and economic indices recommended the GVL/NaOH pretreatment with a molar ratio of 0.1/1. This finding can be extended into the large-scale application of the ensiled maize stover in biogas engineering. Practical guidance can also help optimize the anaerobic digestion of the ensiled maize stover for renewable energy. A technically feasible direction can be gained in the large-scale and efficient conversion of agricultural residues. Moreover, more sustainable agricultural waste management can greatly contribute to greenhouse gas emissions and the circular economy. A viable pathway can also be expected to enhance the economic and environmental sustainability of bioenergy production.