Hypercoagulability and excessive platelet activation account for a significant percentage of mortality and morbidity in cancer patients. In order to test the hypothesis that preloading infusion (PLI) with 6% hydroxyethyl starch 200/0.5 (HES 200), or 6% hydroxyethyl starch 130/0.4 (HES 130) solution can attenuate the hypercoagulable state and inhibit excessive platelet activation of patients with colon cancer, we selected 35 colon cancer patients undergoing laparoscopic-assisted radical colectomy. They were received randomly a test of 15 ml/kg of either HES 200 (n = 17), or HES 130 (n = 18) over a 30-min period preoperatively. In addition, fifteen healthy volunteers were selected as normal control group. Coagulation function was assessed by thrombelastography (TEG), platelet glycoprotein IIb/IIIa and CD62P was analyzed by flow cytometry before PLI, the end of PLI, 1 h after PLI, and 1 h after the end of surgery. Results demonstrated that hypercoagulable state indicated by TEG and excessive platelet activation was found in patients with colon cancer. We found that preloading infusion with HES 200/0.5 can inhibit platelet activation, and the two solutions, especially HES 200/0.5, compromised TEG parameters that indicated hypercoagulability of patients with colon cancer during perioperative period.