Background: Malnutrition is one of the health problems in the elderly population, which increases the risk of poor clinical outcomes. The purpose of this investigation was to evaluate the nutritional status and cognitive function of an elderly Chinese population, to explore the association between malnutrition and cognitive condition as well as the cognitive domain.Methods: A cross-sectional study was conducted in 2365 participants aged 60 years or above from January 2013 to September 2019. We used the Mini Nutritional Assessment Short Form (MNA-SF), and the Mini Mental State Examination (MMSE) to assess the impact of malnutrition on cognitive function.Nutrition-associated factors were analyzed.Results: 33.45% of the participants were identified as malnutrition risk and 5.54% were malnourished, while 36.74% had cognitive impairments. 48.63% had nutritional deficits and 53.65% had cognitive impairment in those over 80 years old. Malnutrition is associated with global cognition (ρ= 0.349, P < 0.0001) and the cognitive domain particularly in orientation (ρ= 0.343, P < 0.0001). The impact was extended to attention and calculation (ρ=0.310, P < 0.0001) as well as language (ρ= 0.302, P < 0.0001) of those over 80 years of age. Malnutrition is an independent risk factor for cognitive impairment after adjusting for other variables (OR=2.004, 95% CI: 1.621-2.479).Conclusion: The prevalence of malnutrition and cognitive impairment was relatively high and increased with age. Malnutrition leads to cognitive decline and disorientation, and also contributes to attention problems, calculation problem and language impairment in the oldest old. Thus, clinicians should assess the nutritional and cognitive status of the elderly regularly to the early dictation and timely intervention.