Objective To explore the method for grading the degree of uterine adhesion in a rat model. Methods A rat model of uterine adhesion was established using the double-injury method. Paraffin sections were observed using HE staining and Masson staining to compare morphological changes in the uterus, endometrial thickness, gland and vessel counts, uterine cavity area, and adhesion severity. Rat sections were classified into three grades based on uterine cavity area for comparative analysis. Results The average uterine cavity area and uterine cavity area/endometrial layer area were smaller in rats in the model group compared with the blank group (P<0.01). The uterine cavity area/endometrial layer area ratio was categorized into grades Ⅰ, Ⅱ, and Ⅲ, with a significant difference among the grades (P<0.05, P<0.01). Conclusions The uterine cavity area/endometrial layer area ratio may reflect the grading difference in the degree of uterine adhesion in rats with uterine adhesions. This ratio may thus be used as a grading-evaluation criterion in the rat model of uterine adhesion, with implications for diagnostic grading in this model.