Objective To investigate the relationship between the level of the soluble triggering receptor expressed on myeloid cell (sTREM⁃1) in the gingival crevicular fluid (GCF) of individuals and peri⁃implantitis. Methods 46 pa⁃ tients (75 implants) with different severities of peri⁃implantitis and 18 patients (75 implants) without peri⁃implantitis were selected in this study. The concentrations of sTREM⁃1 in GCF with different types of peri⁃implantitis were detected by enzyme⁃linked immunosorbent assay (ELISA). The peri⁃implantitis peroxidase depth (PPD), the distance from the shoul⁃ der of the implant to the bottom of the bony defect (DSB), the modified sulcus bleeding index (mSBI) and the modi⁃ fied plaque index (mPLI) were recorded. The correlation between PPD, DSB, mSBI, mPLI and sTREM⁃1 was analyzed. Results The concentrations of sTREM⁃1 in GCF in mild, moderate and severe peri⁃implantitis group were significant⁃ ly higher than those in healthy group (P 0.05). In addi⁃ tion, there was a significant positive correlation between the concentration of sTREM ⁃ 1 and PPD, DSB, mSBI, mPLI. Conclusions The concentration of sTREM ⁃1 in GCF is closely related to the severity of tissue inflammation around implant.