The invention discloses a 2s-4b protein in a peanut 2s albumin component, and a production method thereof. The method comprises the following steps: designing a pair of degenerate primers according to the analytic results of the dimensional electrophoresis of a peanut 2s protein obtained in the laboratory of the inventers and the MS mass spectrum of 2s-4b, and cloning a 2s-4b gene through adopting an RACE method; and constructing a Pet-32a-2s-4b fusion expression vector, inducing to obtain a 2s-4b fusion protein, and carrying out renaturation and enterokinase enzyme digestion of the 2s-4b fusion protein to obtain the 2s-4b protein having the activity of a protease inhibitor. The 2s-4b protein can induce the apoptosis of pulmonary adenocarcinoma A549 cells, and the apoptosis mechanism of the 2s-4b protein is researched. The 2s-4b protein has a wide application prospect, has the characteristics of efficient expression in Escherichia coli, good stability, high purity and high activity, and is suitable for large-scale and industrial production.