Background The aging population in China faces a critical challenge due to the high risk of progression from mild cognitive impairment (MCI) to dementia. Existing MCI screening methods are limited by high costs or reliance on specialized professionals, hindering large-scale implementation. Objective To investigate the diagnostic efficacy of the self-help cognitive assessment test (SCAT) for MCI screening in older adults and provide a practical tool for early identification in large-scale settings. Methods The study recruited cognitively normal and MCI elderly individuals aged 60-80 years from a tertiary hospital and communities in Beijing from March to October in 2024. All participants were clinically diagnosed by neurologists using standardized criteria. SCAT, the Montreal Cognitive Assessment Beijing version (MoCA-BJ) were administered. Receiver operating characteristic (ROC) curve analysis was performed to evaluate SCAT's diagnostic performance (sensitivity, specificity). Correlations between SCAT and MoCA-BJ were assessed. Results A total of 205 cognitively normal elderly individuals and 65 elderly individuals with MCI were included in this study. Compared with the MCI group, the cognitively normal group had a higher proportion of individuals with high - level education and a lower proportion of those with junior high school education (χ² = 29.224, P＜0.001). There were no significant differences in other general data between the two groups (P＞0.05).The SCAT total score in the MCI group was (37.89±7.81), which was significantly lower than that in the cognitively normal group (50.01±10.00) (P＜0.001, Cohen's d =1.269). The optimal cutoff score of SCAT for screening MCI from the elderly individuals with normal cognitive function was 43 points. At this cutoff, the area under the ROC curve (AUC) was 0.833 (95% CI: 0.776 - 0.891), with a sensitivity of 0.780 and specificity of 0.757 for diagnosing MCI. SCAT total scores showed moderate correlations with MoCA-BJ (r =0.482, P＜0.001). Conclusion SCAT demonstrates acceptable diagnostic efficacy in MCI screening for MCI among older adults, with additional advantages of self-administration and mobile application convenience, making it suitable for large-scale screening initiatives.