As stimulation points in acupuncture,acupoints have unique local pathological characteristics. Acupoint sensitization is the transformation of an acupoint from a ‘silent state’ to an‘activ ated state’ and the specificity of sensitization is important for disease investigation, and its dynamics vary significantly with the degree of sensitization.The mechanism of action of l ocal acupoints on the skin needs to be further clarified to provide reference value for sub sequent acupuncture treatment.To explore the degree of acupoint sensitization relatedto the and the underlying mechanism of local content of small biomolecules, mainly mastcells.We established a knee osteoarthritis (KOA) model by intra-articular injection of sodiumiodoac etate (MIA) into the left knee of rats.The distal points of the extremities (Left Tianjing,Ri ght Tianjing,Left Heding,Right Heding)were selected for the study.The mechanical pain thre shold at local acupoints was detected by Electric Von Frey, and the aggregation andthreshi ng status of mast cells(MCs) were detected by toluidine blue staining.The MCs aggregatio n and degranulation status of each group were detected by toluidine blue staining;the chan ges in the content of trypsin, 5-HT and HA indexes at different activation points weredete cted by immunofluorescence double-labeling method.It showed that the content of trypsin, 5-HT and HA at different activated acupuncture points varied more than the resting state of the local acupuncture points, with the right Tianjing acupoint having a higher content t han the other points, indicating that the number of MCs and the content of trypsin, 5-HT and HA produced by degranulation may be one of the cellular mechanisms occurring dur ing acupuncture point sensitization. The pain thresholds of different acupoints were signific antly different, and the sensitization degree was in the order of right Tianjing acupoint(SJ 10)>right Heding acupoint(EX-LE2)>left Heding acupoint(EX-LE2)>left Tianjing acu point(SJ10).It indicated that the sensitization differences clarify the degrees of variationw ith the differences in point selection,which helped to broaden the understanding ofthe char acteristics of local points and explore the basic pathology of localpoints and provided som e theoretical basis for clinical intervention selection.