Abstract: Objective:To evaluate the effect of therapeutic communication on the illness uncertainty of preoperative patients with colorectal cancer.Methods:Sixty-seven patients with primary colorectal cancer were divided into the experimental group(35 cases) and the control group(32 cases).All the patients received routine preoperative care and communication.In addition,therapeutic communication was provided for the experimental group.The illness uncertainty was evaluated at admission afternoon and the day before operation.Results:Total uncertainty and four factor scores of two group had no significant differences before the intervention(P0.05).After the intervention,the scores of uncertainty,ambiguity,lack of information and complexity of experimental group were significantly lower than those of the control group(P0.05 to P0.01).There was no significantly difference in the scores of unpredictability(P0.05).Conclusions:Nursing intervention based on the therapeutic communication system is an effective approach in reducing the illness uncertainty of preoperative patients with colorectal cancer