Objective To investigate the effect of combination of breast conserving surgery and sentinel lymph node biopsy in the treatment of early breast cancer and compare it with the effect of modified radical mastectomy. Methods A total of 100 cases of early breast cancer admitted from September 2021 to September 2023 were included and divided into 50 cases of control group and 50 cases of observation group by random number table method. The control group underwent modified radical mastectomy, and the observation group underwent breast conserving surgery combined with sentinel lymph node biopsy. Outcome measures included perioperative indicators, incidence of complications, cosmetic satisfaction and quality of life at postoperative 12 months, and postoperative tumor markers [carbohydrate antigen 19-9 （CA19-9）, carcinoembryonic antigen （CEA）, and cytokeratin 19 fragment antigen 21-1 （CYFRA21-1）]. Results Compared with the control group, the intraoperative blood loss and drainage volume were lower, and the operation time, drainage tube removal time, and postoperative hospital stay were shorter in the observation group, and the differences were statistically significant （P<0.05）. The incidence of complications in the observation group was lower than that in the control group （P<0.05）. The observation group showed significantly higher satisfaction with cosmetic results and quality of life scores than the control group （P<0.05）. No differences were found in CA19-9, CEA, and CYFRA21-1 levels between the two groups of patients before treatment （P>0.05）; after treatment, the tumor marker levels in both groups decreased, and the observation group had lower levels than the control group （P<0.05）. Conclusion Breast conserving surgery combined with sentinel lymph node biopsy has a prominent effect in the treatment of early breast cancer patients. The combined surgery is not only close to modified radical mastectomy in terms of effect, but also reduces the risk of surgical complications, effectively maintains breast shape, conducive to improving the quality of life after surgery, and has a high cosmetic satisfaction, which is worthy of promotion and application.