To enhance the applicability and precision of nitrogen，phosphorus，and potassium element analysis in biochar-based organic fertilizers，this study conducted a comparative analysis of two digestion methods:the sulfuric acid-hydrogen peroxide digestion method outlined in the NY/T 3618—2020 standard Biochar-Based Organic Fertilizers，and the microwave digestion method. This study optimized the acid system ratio in the microwave digestion method through a response surface experimental design，the optimal acid system ratio of biochar-based organic fertilizer samples was 5 mL H2SO4+1 mL HClO4+2.5 mL HF，thereby developing a novel microwave digestion approach suitable for the analysis of biochar and its related products. Compared with the standard method，the verification experiment results showed that the relative standard deviation of the samples measured by microwave digestion method was 0.04%-0.37%，which was lower than the standard method. The experimental results demonstrated that for biochar-based organic fertilizer samples，the microwave digestion method could not only offer higher digestion efficiency but also provide better reproducibility in detection results，with a significant advantage in analysis duration.