Objective: To evaluate the diagnostic value of the combined detection of D-dimer (D-D) and thrombin time (TT) in exclusion of deep venous thrombosis (DVT) of lower extremity in patients with peritoneal carcinomatosis. Methods: Two hundred and forty-one patients with peritoneal carcinomatosis treated between May 2015 and May 2017 were enrolled. The variables of coagulation and fibrinolysis of the patients before operation were determined. The likelihood of DVT of the patients was evaluated by using Wells clinical model. All patients received venous ultrasonography of the lower extremities for DVT diagnosis, and the events of symptomatic venous thromboembolism (VTE) during perioperative period were observed. Results: Of the 241 patients, 21 cases (8.7%) were diagnosed as DVT of lower extremity by venous ultrasonography. No symptomatic VTE events occurred during the postoperative follow-up period in any of the patients. In patients with DVT compared with those without DVT, the TT was significantly shortened, and levels of fibrin/fibrinogen degradation products and D-D were significantly increased (all P<0.05). As determined by the ROC curve, the optimal cut-off value of TT for diagnosing DVT in patients with peritoneal carcinomatosis was 13.55 s, and its negative predictive value was 100% and in combination with D-D detection the rate of missed diagnosis was 0. Regardless of high or low probability of DVT assessed by Wells scoring, the negative predictive value of this combined detection was 100%. Conclusion: There is certain incidence of lower extremity DVT in patients with peritoneal carcinomatosis at admission. The combined detection of D-D and TT has strong negative predictive value for exclusion of DVT, which is independent on Wells score. Lower extremity DVT can be safely excluded in those with negative result from the combined detection (D-D<243 ng/mL DDU and TT>13.55 s) without confirmation by venous ultrasonography.