Objective To study magnetic resonance diffusion weighted imaging in the interventional therapy of liver cancer clinical effect and application value. Methods Our hospital diagnosed with liver cancer interventional treatment of patients with 23 cases as the research object, respectively in the interventional treatment before and after treatment the timing of the 7 d for patients undergoing routine scan and magnetic resonance diffusion weighted imaging scans, observe the imaging characteristics of patients, and compare the different diffusion sensitive gradient value (b) the average ADC values of tumor area. Results The liver lesion location has high signal or high signal, a week after the end of the treatment, lesion area on T2WI with dot or flake low signal, DWI is given priority to with low signal on the can. Before and after treatment of tumor volume, respectively (203.92+121.88) cm3 and cubic centimeter (146.38-118.29). Comparing statistically significant, and P<0.05. B=1000 s/s/was and 1300 was when the image quality is poorer, ADC values cannot be measured accurately. B=50 s/s/was and 100 was the average ADC values before and after the treatment is no statistical difference (P>0.05). B= 300 s/s/was 500 and 700 was, s/was, on average, ADC values increase with b is increasing, and the average ADC values before and after the treatment the comparison between statistically significant (P<0.05). Conclusion Magnetic resonance diffusion weighted imaging can reflect the microscopic changes in the form of tumor effectively, select the appropriate diffusion sensitive gradient value choice to obtain a better signal contrast, can be based on the change of cell density, the density of tumor blood vessels in patients with hepatocellular carcinoma after interventional therapy of pathological physiological changes, assessment of therapeutic effect, worthy of clinical popularization and application.