Objective To investigate the diagnostic value of inflammatory indicators for sarcopenia in patients with colorectal cancer. Method A cross-sectional study of 410 patients with colorectal cancer who were admitted to the Department of Gastrointestinal Surgery Affiliated Hospital of Southwest Medical University from December 2019 to December 2021 was conducted. The patients were divided into sarcopenia group and non-sarcopenia group by the skeletal muscle index SMI of the third lumbar vertebrae. Platelet to lymphocyte ratio PLR neutrophil to lymphocyte ratio NLR and systemic immune inflammatory index SII were used to evaluate systemic inflammation. Multivariate logistic regression analysis was used to analyze the influence of systemic inflammatory indicators on the risk of sarcopenia in colorectal cancer patients. The receiver's operating characteristic ROC curve is used to determine the best cut-off value of inflammatory indicators and to judge its sensitivity and specificity. Result Among 410 patients with colorectal cancer 232 56. 60% were in the sarcopenia group and 178 43. 40% were in the non - sarcopenia group. Compared with the non - sarcopenia group the sarcopenia group had higher NLR PLR and SII lower body mass index and albumin levels longer hospitalization time and higher total costs and complication rates P<0. 05 . Regression analysis showed that PLR≥172. 00 OR = 1. 78 95%CI = 1. 17-2. 72 P= 0. 007 was an independent risk factor for sarcopenia in colorectal cancer patients. The ROC curve showed that the best cut -off value of PLR in predicting the risk of sarcopenia was 185. 12 the sensitivity was 52. 20% and the specificity was 66. 90% . Conclusion In colorectal cancer patients high PLR increases the risk of sarcopenia which has certain diagnostic value for sarcopenia.