The work aims to create a slow-releasing solid chlorine dioxide preservative with high stability and a long effective sterilization period, to solve the issues in the existing chlorine dioxide slow-releasing preservative, such as substantial release fluctuations and difficulty in usage. With polyurethane serving as the slow-releasing substrate as the base material and sodium chlorite as the main material, a moisture-sensitive chlorine dioxide slow-releasing preservative was created by a one-way test combined with an orthogonal experiment. The optimal dosage of activator DMPA was found by evaluating the acid value of the substrate. The effects of sodium chlorite addition, particle size, and relative humidity on the release capability of the preservative were studied, and its surface morphology and interior structure were observed. At 50% of relative humidity, 1.5 g of sodium chlorite, and 250-300 of mesh particle size, the total amount of chlorine dioxide released was high, and the release fluctuated smoothly. There was no violent release phenomenon. In this study, a slow-releasing solid chlorine dioxide preservative has been developed to achieve long-term slow release of chlorine dioxide.