Abstract: To elucidate the microbial diversity in spoiled pickled radish, high-throughput sequencing of 16S rDNA / ITS sequences was used to analyze bacterial and fungal diversities in fresh, early-spoilage and late-spoilage pickled radish. Then, six preservatives, namely odium benzoate, Candidapotassium sorbate, sodium dehydroacetate, sodium diacetate, nisin, and ε-polylysine, were selected. The preservative formula was optimized through single-factor experiments and orthogonal experiments. The results of microbial diversity analysis show that compared to fresh samples, early-spoilage samples exhibit a significant reduction in microbial diversity, where Lactobacillus and Kazachstania become dominant while other genera decline substantially in relative abundance. The microbial diversity in late-spoilage pickled radish slightly increases compared with early-spoilage samples, with the relative abundance of Candida significantly increasing. Concurrently, genera with initially low abundances including Weissella, Acinetobacter, Pediococcus, Mycosphaerella, Diaporthe and Alternaria exhibit marginal increases. The experimental results show that all six preservatives inhibit the mixed microbial consortium, identifying the optimal composition as 0.40 g/kg sodium dehydroacetate, 0.10 g/kg nisin, and 0.06 g/kg ε-polylysine. This compound preservative extends product shelf life by more than threefold compared to the preservative-free control.