Elucidating antibody sequences is crucial for understanding antigen binding and advancing therapeutic and research applications. However, current de novo sequencing technology is hindered by high costs, low throughput, missing ion information, and assembly limitations in accuracy and robustness. Here, we developed a refined sequencing solution by integrating Single-Pot Multi-Enzymatic Gradient Digestion (SP-MEGD) with a beam search-based assembler (Fusion) to decipher complete sequences. This solution achieved high accuracy (over 99%) in antibody reconstruction. Biological validation of multiple commercial antibodies with unavailable sequences further supports its effectiveness. Additionally, our solution can discriminate and achieve over 99% accurate sequence coverage of mixtures containing two or three COVID-19 neutralizing antibodies. To our knowledge, this is the first study to enable simultaneous sequencing of multiple antibodies using only bottom-up mass spectrometry, improving throughput without increasing duration or expense. In summary, our method advances antibody research by enhancing the accuracy and efficiency of complex antibody sequencing.