<p class="abstract"><strong>Background:</strong> Malnutrition is common in patients with cancer, which adversely affects the survival and quality of life of cancer patients. However, there is no national data on the prevalence of malnutrition in Chinese cancer patients. This study aims to evaluate the prevalence of malnutrition and quality of life (QOL) of Chinese patients with local regional, recurrent or metastatic cancer, to address the prognostic value of nutritional status and QOL on the survival of cancer patients in China and to validate the patient-generated subjective global assessment (PG-SGA) questionnaire in Chinese cancer patients.</p><p class="abstract"><strong>Methods:</strong> This is an observational, multi-centered, and hospital-based prospective cohort study. We aimed to recruit 50,000 cancer patients (age 18 and above) over an 8-year period. Data collection will occur within 48 hr after patients are admitted to hospital, 30-days after hospital admission, and the follow-up will be conducted 1-8 years after enrolment. The primary outcome is overall survival, and secondary outcomes are length of hospital stay and hospital costs. Factors measured are demographic characteristics, tumor characteristics, anthropometry measurements, hematological measurement, body composition, PG-SGA scores, Karnofsky performance status scores, and QLQ C30 scores. This protocol was approved by local ethical committees of all the participant hospitals.</p><p class="abstract"><strong>Conclusions: </strong>This multi-centered, large-scale, long-time follow-up prospective study will help diagnose malnutrition in cancer patients in China, and identify the related risk factors associated with the negative outcomes. The anticipated results will highlight the need for a truly scientific appraisal of nutrition therapy, and help to improve outcomes among cancer patients in China.</p><p class="abstract"><strong>Trial Registration: </strong>The trial has been registered with the Chinese Clinical Trial Registry, ChiCTR1800020329. Registered on 19 December 2018.<strong></strong></p>