Objective To study the application value of DWI combined with routine magnetic resonance imaging in the follow-up of patients with primary liver cancer after treatment. Methods 60 cases of patients with primary liver cancer treated in our hospital from January 2012 to January 2015 were treated as the research objects. DWI combined with routine magnetic resonance imaging was performed in 1 week before and after treatment and 1 year after operation. The ADC values of different corresponding b values were recorded and compared in 1 week before and after treatment and 1 year after operation. The characteristics of MR-DWI signal in patients with primary liver cancer after operation were summarized. The detection rate of recurrent tumor foci was calculated. Results MR-DWI of the 60 patients with primary liver cancer before operation showed high signals in tumors. 1 week after operation, DWI showed low signals in the lipiodol depositional areas and tumor necrosis areas. Combined with routine magnetic resonance imaging, it showed high signals in tumor necrosis areas on T2WI and high signals in non-depositional lipiodol solid parts of the tumors. 1 year after surgery, 48 recurrent lesions of the 50 ones were detected and the detection rate of recurrent lesions was 96% (48/50). 26 new lesions showed high signal. 1 week after operation, the ADC values of different corresponding b values were higher than those before operation (P<0.05). At the end of 1 year of follow-up, the ADC values of different corresponding b values decreased and were lower than the ADC values in 1 week after operation but they were still higher than those before operation (P<0.05). Conclusion DWI combined with routine magnetic resonance imaging is easy to operate, with fast imaging and without radiation injury. It can sensitively showed the lesions of liver cancer. The application in the follow-up of primary liver cancer is of higher detection rate of recurrent lesions, which is beneficial to evaluate the recurrence during postoperative follow-up. The application value is high.