Abstract: Microbial fermentation can effectively improve the gel strength of freshwater fish surimi. Tilapia surimi has low gel strength and is prone to gel deterioration during processing. In order to develop high-quality fermented surimi products from tilapia we used Lactiplantibacillus plantarum as a fermentation strain to explore the effect of strain addition on the gel strength of fermented surimi. After adding fermentation strain, the gel strength of fermented surimi was significantly improved, while the contents of most free amino acids and total amino acids significantly decreased. The effect of strain addition on the microbial community in the fermented surimi was studied by 16S rRNA gene high-throughput sequencing. During fermentation with strain, Lactiplantibacillus remained to be the dominant genus, increasing to 63.71% at the end of fermentation, while the abundance of other spoilage microorganisms was significantly inhibited. Besides, the total plate count in the fermented surimi was significantly lower than that in the naturally fermented surimi. The correlation network maps at different fermentation stages show that the gel strength was significantly negatively correlated with the total plate count and total amino acid content during the whole fermentation period. Only Lactiplantibacillus was significantly negatively correlated with the total plate count and total amino acid content but was positively correlated with gel strength. The results indicate that the improved gel strength mainly results from the inhibited growth of spoilage microorganisms and hydrolysis of surimi proteins by L. plantarum. L. plantarum can be used as a special starter to develop the fermented tilapia surimi products with high quality.