Objective To evaluate the clinical value of 18 F-FDG PET/CT for restaging, guiding therapeutic strategy and predicting prognosis in patients with postoperative colorectal cancer (PCC). Methods Records of 91 patients (51 males, 40 females;average age (54.90±11.47) years) in whom PCC were eval-uated by 18 F-FDG PET/CT imaging from May 2010 to June 2014 were retrospectively reviewed. All patients underwent evaluation at the First Affiliated Hospital of Soochow University. 18 F-FDG PET/CT results were compared with the results from pathological examination, clinical long-term follow-up (≥6 months ) and conventional imaging. Diagnostic efficiency of 18 F-FDG PET/CT in detecting recurrence and metastases of PCC were calculated. The clinical value of 18 F-FDG PET/CT in restaging and guiding therapeutic strategy were analyzed in patients with true positive results. Kaplan-Meier survival analysis was conducted based on the results of PET/CT and the alteration of therapeutic strategy after PET/CT. Results The sensitivity, specific-ity, accuracy, positive predictive value and negative predictive value of 18 F-FDG PET/CT were 96. 36%(53/55), 83.33%(30/36), 91.21%(83/91), 89.83%(53/59) and 93.75%(30/32), respectively. The median survival time and the 5-year survival rate were 10.00 years and 84% in patients with true negative PET/CT results, and were 6. 33 years and 53% in true positive group. Patients with true negative results showed longer OS and PFS than those with true positive results (χ2=7.753, 8. 933, both P<0.01). Among the 53 patients with true positive PET/CT results, tumor restaging was up-regulated in 32 patients and down-regulated in 2 patients. Therapeutic strategies were changed in 33 patients, in whom the PFS was lon- ger than those without treatment alteration (χ2=4.905, P<0.05) . Conclusion 18 F-FDG PET/CT imaging has the high sensitivity and accuracy in detecting recurrence and metastasis of PCC, with the potential for altering clinical restaging and therapeutic strategy timely.