Purpose: To study the adverse effects of frailty on elderly cancer patients and explore effective interventions. Methods: The convenience sampling method was used to select 362 elderly cancer patients who were consecutively admitted to the Oncology Department of the Affiliated Hospital of Hebei University from April 2020 to March 2021. The patients had five physical dimensions of activity tested and were divided into a frail group (n = 128) and a non-frail group (n = 234) based on the test results. The Chinese version of the Vulnerable Elders Questionnaire was formed on the basis of the Vulnerable Elders Survey-13 (VES-13). The two groups of patients were surveyed within three days of admission. The questionnaire includes general information (age, gender, education level, marital status, monthly income, living area, smoking, and alcohol history, hearing, vision, and sleep status), Geriatric Depression Scale (GDS), Mini Nutritional Assessment (MNA), Mini-Mental State Examination (MMSE), and Charlson Comorbidity Index (CCI). Results: (1) By comparing the general information of the two groups of patients, it was found that the gender, education level, marital status, living area, and history of tobacco and alcohol had no statistical significance (P > 0.05). In contrast, the frail group’s age, hearing status, vision status, and sleep status are significantly worse than those of the non-frail group (P < 0.05); (2) Analysis of Vulnerable Elderly Questionnaire results found that the GDS scores in the frail group were higher than those in the non-frail group, and the MNA and MMSE scores were lower than those in the non-frail group (P < 0.05). This indicated that the patients in the frail group had more severe depression, poor nutritional status, and specific impairments in cognitive function. Conclusion: Frailty adversely affects elderly cancer patients, and effective measures should be taken to intervene.