Objective To investigate the value of magnetic resonance multisequence imaging in guiding breast conserving surgery after neoadjuvant chemotherapy for triple negative breast cancer （TNBC）. Methods A total of 98 patients with TNBC admitted to Sanming Second Hospital in Fujian Province from June 2018 to June 2023 （all receiving neoadjuvant chemotherapy） were selected and randomly divided into a control group and an observation group by random number method. Among them, 49 patients underwent ultrasound body surface localization and were included in the control group, and the other 49 patients underwent magnetic resonance multisequence imaging and were included in the observation group. Both groups underwent breast conserving surgery to compare the application value of different imaging techniques for the surgery. Results The preoperative estimated maximum diameter of the tumor and the tumor/breast volume in the observation group were smaller than those in the control group （P<0.01, P<0.05）, and the coincidence rate with the actual surgical resection of the tumor volume and the negative margin rate in the observation group were higher than those in the control group （P<0.05）. There was no difference in surgical time and incidence of complications between the observation group and the control group （P>0.05）. Conclusion Magnetic resonance multisequence imaging has an important value in guiding breast conserving surgery in TNBC patients after neoadjuvant chemotherapy, providing an accurate resection range, and having a low incidence of complications, which is worth promoting.