The work aims to make a more convenient prediction of the spoilage degree of pork. Bromocresol purple was selected as a pH indicator to reflect the freshness of pork. Glycerin was added to make mixed gas-sensitive gel. Cotton fiber paper was used as the substrate to prepare indicator paper. The indicator was coated on the substrate by coating equipment. Then, the prepared indicator paper was applied to pork. The results showed that the optimum process combination was obtained by response surface analysis, with hydroxyethyl cellulose addition of 1.70 g/(100 g), glycerol addition of 5.00 mL/(100 mL), indicator solution addition of 9.00 mL/(100 mL) and coating thickness of 4 mm. The spoilage degree of pork is consistent with the color change of pH indicator paper, which has certain practical application value.