Objective This Paper is to investigate the application value of magnetic resonance diffusion weighted imaging in interventional therapy of liver cancer. Methods Thirty two patients with liver cancer admitted by the Radiology Department of the Hospital undergoing interventional treatment of liver cancer patients were selected as research objects, who were retrospectively analyzed and summarized according to clinical data, those patients underwent routine scanning and magnetic resonance diffusion weighted imaging scanning respectively before interventional treatment and 7 days after interventional treatment, imaging characteristics of patients were observe, and ADC indexes under different diffusion sensitive gradient values (b) were compared. Results The gross tumor volume of patients before treatment 204.93+/-122.89cm3 , and it fell to 145.37+117.26cm2 after treatment, the gross tumor volume of patients after treatment was significantly lower than that of patients before treatment (p<0.05), and differences were significant. There was no significant difference in ADC indexes before and after the treatment when the value of b hit 50 and 100, and there were significant differences in ADC indexes before and after the treatment when the value of b hit 300, 500 and 700 (p <0.05). Conclusions Magnetic resonance diffusion weighted imaging deliver great value in interventional therapy of liver cancer, its images deliver certain characteristics, insignificant changes in the form of tumor may be reflected, and pathological change in tumor vascular density of patients may be observed, and the evaluation on treatment efficacy is of high application and promotion value in clinical practices.