The aim of this study was to identify and quantify microplastics in blood, stool, and tumor surgical specimens from gastric cancer patients by analyzing the nature, type, and abundance of microplastics using laser direct infrared (LDIR) spectroscopy, scanning electron microscopy (SEM), and pyrolysis-gas chromatography-mass spectrometry (Py-GC/MS). Meanwhile, combining macro-genomic and metabolomic techniques to explore the association between microplastics and host microbiota and metabolic profiles, and to reveal the potential effects of microplastics on gastric cancer incidence and development will provide new insights into the relationship between microplastic contamination and gastric cancer, as well as an important scientific basis for future public health strategies and cancer prevention and control measures.