Objective To investigate the predictive value of mid-upper arm circumference MAC and calf circumference CC for sarcopenia in patients with colorectal cancer CRC . Method This is a cross-sectional study that includes 372 patients who were diagnosed with CRC for the first time at the Department of Gastrointestinal Surgery Affiliated Hospital of Southwest Medical University from April 2022 to August 2023 with appendicular skeletal muscle mass ASM and appendicular skeletal muscle mass index ASMI measured by bioelectrical impedance analysis BIA and MAC CC hand grip strength and 6-Meter Walk test measured with comparison of basic conditions by grouping by sarcopenia. Grouped by gender ROC curves were used to compare the predictive value of MAC and CC for sarcopenia in patients with CRC and to determine the optimal cut-off value and Kappa values were calculated to determine the consistency of MAC and CC with the diagnostic criteria for sarcopenia. Result Among 372 CRC patients 233 62. 6% were male and 139 37. 4% were female and 81 21. 8% were diagnosed with sarcopenia. The ROC curves showed that the optimal cut-off values for MAC to predict sarcopenia were 24. 9 cm in males sensitivity 81. 8% specificity 73. 0% and 23. 7 cm in females sensitivity 80. 8% specificity 72. 6% and for CC to predict the best cut - off values for sarcopenia were 32. 4 cm sensitivity 74. 5% specificity 80. 9% in men and 31. 0 cm sensitivity 88. 5% specificity 66. 4% in women. The AUC values of MAC CC and the combination of the two for the prediction of sarcopenia were 0. 824 0. 851 0. 864 for male patients and 0. 819 0. 801 0. 828 for female patients respectively which showed a higher value of the combined one. Comparing with the diagnostic criteria of sarcopenia the Kappa values of MAC and CC were 0. 443 0. 493 for male and 0. 385 0. 334 for female respectively. Analysis by gender age history of smoking alcohol consumption clinical stage and body mass index BMI subgroups revealed that mPG-SGA showed strong consistency for good/ mild malnutrition moderate malnutrition and severe malnutrition among patients with BMI<18. 5 kg / m 2 Kappa=0. 762 P=0. 001 . All subgroups with the exception of BMI<18. 5 kg / m 2 showed almost perfect consistency for the three different nutritional stages Kappa>0. 9 P<0. 001 . Conclusion Both MAC and CC have good predictive value for sarcopenia in patients with CRC and the combination of them has a better predictive effect.