Emotional numbing is a debilitating response to traumatic stress, but no scale has yet to be validated for use among Chinese populations. The aim of the study is to revise and validate a brief measurement of emotional numbing and test the clinical significance of emotional numbing among Chinese adults. A total of 3,230 participants enrolled in this study during a city-wide lockdown caused by the COVID-19 pandemic in Shanghai, China. The general subscale of the Emotional Reactivity and Numbing Scale (ERNS) was used to assess emotional numbing. Cronbach's αs were calculated to examine each item’s contribution to the measurement reliability. A unidimensional graded response model was estimated to evaluate the item-level performance and validity from an item-response theory (IRT) perspective. Informed by the reliability test and the IRT analysis, a four-item ENRS-C scale was found to be a reliable and valid measurement. Regression models were used to examine pandemic-related stressors and mental health correlates of emotional numbing. Emotional numbing was associated with intimate partner violence, bereavement, stressful life events and mental health outcomes including self-reported depression symptoms, anxiety symptoms, psychological well-being, and sleeping problems. This study highlights emotional numbing as a mental health condition associated with major life stressors and has significant clinical and functional implications. Additional studies are needed to investigate how emotional numbing in China is shaped by sociocultural contexts that discourage the expression of socially disruptive emotions.