Objective: To analyze the dental plaque microecological characteristics and the levels of salivary interleukin (IL)-5, IL-12, and IL-16 in school aged children with mixed dentition, providing a theoretical basis for the prevention and control of childhood dental caries. Methods: A total of 199 school aged children admitted aged 6-12 years to Tianjin Stomatological Hospital from January 2023 to January 2025 were selected. According to the decayed missing and filled teeth(DMFT) index, they were divided into high caries group ( n =68, DMFT index≥4), low caries group ( n =65, 1≤DMFT index≤3) and caries free group ( n =66, DMFT index=0). The microbial composition of dental plaque was analyzed by 16S rDNA high throughput sequencing. Salivary levels of IL-5, IL-12 and IL-16 were detected by enzymelinked immunosorbent assay kit. Pearson correlation test was used to analyze the correlation between levels of salivary IL-5, IL-12 and IL-16 and the DMFT index in children with caries. Results: Species richness and evenness (Shannon index) and uniformity (Shannonevenness index) in the high caries group were (3.28±0.64) and (0.61±0.13), respectively, which were lower than (3.66±0.52) and (0.74±0.15) in low caries group, and ( 3.60± 0.49) and (0.72±0.16) in caries free group ( F =9.08, 15.20, both P <0.05). The relative abundances of Firmicutes and Actinobacteria in the high caries group were higher than those in the low caries and caries free groups, while the relative abundances of Bacteroidetes, Fusobacteria, and Candidate phylum TM7 were lower than those in the low caries and caries free groups. The relative abundances of Streptococcus, Leptotrichia, Veillonella, Prevotella, and Actinomycesin in the high caries group were higher than those in the low caries and caries free groups, while the relative abundances of Capnocytophagaand Porphyromonas were lower ( F = 47.55- 1 969.24 , all P <0.05). The levels of salivary IL-5, IL-12, and IL-16 in the high caries group [(12.57±3.21, 28.73±6.79, 45.31 ±11.14)pg/mL] were higher than those in the low caries [(8.63±2.39, 18.16±4.62, 32.60±9.46)pg/mL] and caries free groups [(7.84±2.17, 14.94±3.83, 29.55±8.21)pg/mL] ( F =62.08, 141.23, 49.35, all P <0.05). Pearson correlation test results showed that salivary IL-5, IL-12, and IL-16 levels were positively correlated with the DMFT index in children with caries ( r = 0.73 , 0.68, 0.65, all P <0.05). Conclusions The microecological structure of dental plaque in school aged children with mixed dentition caries is significantly altered, the levels of pro inflammatory factors are significantly elevated, and these levels are positively correlated with the severity of caries.Oral microbial dysbiosis and local inflammatory responses may play a key role in the development and progression of dental caries.