BackgroundSmartphone addiction is prevalent among college students, and there is a concern that the COVID-19 pandemic may bring an increased prevalence of smartphone addiction due to constant online classes and repeat quarantine policies. This study aims to assess the prevalence and influencing factors of smartphone addiction among Chinese nursing postgraduates during the pandemic by examining variables, including loneliness, perceived stress, resilience, and sense of security.MethodsThis online cross-sectional survey recruited 224 nursing postgraduates in four cities in 2022, using Smartphone Addiction Scale for College Students, the Chinese version of Perceived Stress Scale, UCLA Loneliness Scale Version 3, Chinese version of the 10-item Connor-Davidson Resilience Scale, and the Security Questionnaire. Hierarchical regression analysis and logistic regression analysis were performed to explore the associated factors and predictors of smartphone addiction.ResultsDuring the COVID-19 pandemic, the prevalence of smartphone addiction was 10.41%. There was a positive correlation between smartphone addiction and loneliness, perceived stress (P < 0.001), and a negative relationship with resilience and sense of security (P < 0.001). The logistic regression analysis identified five risk factors that contribute to smartphone addiction, including daily duration of using a smartphone (3–5 h) (OR = 11.085, 95%CI = 1.21–101.79), numbers of smartphone (OR = 3.704, 95%CI = 1.33–10.30), perceived stress (OR = 1.163, 95%CI = 1.06–1.28), loneliness (OR = 1.071, 95%CI = 1.01–1.13), age of using a smartphone first time (OR = 0.754, 95%CI = 0.60–0.95). Two protective factors, resilience (OR = 1.098, 95%CI = 1.01–1.20) and sense of security (OR = 0.950, 95%CI = 0.90–1.00), were identified.ConclusionsCollectively, our study found that during the COVID-19 pandemic, smartphone addiction was prevalent among nursing postgraduates, and loneliness and perceived stress are important risk factors for smartphone addiction. Therefore, administrators should adopt targeted interventions to reduce smartphone addiction and the negative impacts on the psychological well-being of nursing postgraduates during a sudden outbreak of a national epidemic crisis.