Objective This study aimed to investigate the comparative efficacy of mPG - SGA PG - SGA and GLIM tools in assessing malnutrition among digestive system tumor patients and analyze correlations between mPG-SGA and hematological parameters in newly admitted patients. Method 105 digestive system tumor patients admitted within ≤48 hours to the department of oncology of our hospital between January and April 2025 were enrolled. Demographic data and hematological parameters were collected routinely. Nutritional status was assessed using mPG-SGA PG-SGA and GLIM criteria. Comparative efficacy was analyzed through Spearman correlation between mPG-SGA scores and nutritional biomarkers. Result The mean age of all subjects in this cohort n = 105 was 58. 50±13. 94 years old with male accounted for 67. 62% 71 cases . Prevalence of malnutrition detected by 3 tools was 40. 00% mPG-SGA 43. 81% PG-SGA and 60. 00% GLIM . Using PG-SGA as reference mPG-SGA showed superior sensitivity 100. 00% vs 82. 61% and specificity 93. 65% vs 57. 63% with higher AUC 0. 957 vs 0. 701 . The Kappa coefficients of mPG-SGA vs PG-SGA mPG-SGA vs GLIM and PG-SGA vs GLIM were κ = 0. 922 κ = 0. 432 and κ = 0. 387 respectively all P <0. 001 . Significant positive correlations emerged between mPG-SGA and lymphocytes r = 0. 246 P = 0. 011 hemoglobin r = 0. 226 P= 0. 020 and skeletal muscle index r = 0. 373 P<0. 001 . Conclusion mPG-SGA demonstrated comparable efficacy to PG-SGA and GLIM in malnutrition assessment with correlation with some nutrition indexes.