Objective:To study the predictive value of preoperative platelet parameters on the occurrence and prognosis of rectal cancer.Methods:659 patients who underwent rectal cancer surgery at Nanjing Hospital of Chinese Medicine from January 2013 to October 2022 were retrospectively selected as the rectal cancer group,while 650 healthy individuals who underwent physical examinations between January 2016 and June 2018 were selected as the control group.The association of age,gender,TNM stage,and preoperative platelet parameters,including platelet count(PLT),mean platelet volume(MPV),platelet distribution width(PDW)and plateletcrit(PCT),with occurrence and overall survival(OS)of rectal cancer patients were analyzed.Results:Age≥60 years(P<0.05,95%CI1.11-1.15),male(P<0.05,95%CI1.17-2.07)and high preoperative MPV(P<0.05,95%CI 1.28-2.31)were independent risk factors for rectal cancer,but there was no obvious correlation of preoperative PLT,PCT and PDW with the occurrence of rectal cancer(P>0.05).Univariate Kaplan-Meier survival analysis showed that preoperative MPV,PLT and PCT were significantly associated with OS of rectal cancer patients(P<0.05).Cox multivariate analysis showed that age,male sex and TNM stage were significant prognostic factors for OS of rectal cancer patients(P<0.05).Conclusion:Age(≥60 years),male,TNM stage and preoperative MPV are independent risk factors for rectal cancer.Preoperative MPV,PLT,PCT and PDW have no clinical predictive value of OS.