Sugarcane leaf (SL) is an attractive lignocellulosic feedstock for methane production by anaerobic digestion (AD), but the resistant structure and irregular components of SL hinder its effective use. To provide a comprehensive understanding of the different SL components, the physicochemical properties, methane production performance, and a techno-economic analysis (TEA) of the mesophyll (SL-MPL) and midrib (SL-MRB) parts of SL were investigated in this study. The results showed that the chemical components, physical properties, and structures of SL-MPL and SL-MRB were markedly different. After AD, SL-MPL showed methane production of 124.2 ± 8.5 mL/g volatile solid (VS), which was 121.4% higher than that of SL-MRB. Besides, the VS removal and hydrolysis rates for SL-MPL were 1.4 and 2.9 times higher than those for SL-MRB, respectively. The AD of SL-MRB was predominantly limited by its high lignin content, low nutrient element contents, smooth surface, and dense spatial structure. The TEA revealed that the revenue from SL-MPL was 74.9% of total revenue in the AD scenario, which was three times that of SL-MRB. Therefore, SL-MPL was more techno-economically efficient than SL-MRB under the AD scenario. This study provides a theoretical basis and data support for the effective utilization of SL.