Objectives: Poststroke cognitive impairment (PSCI) has constituted a heavy public health burden worldwide. Traditional Chinese Medicine (TCM) has been widely used in treating PSCI. This study aimed at validating the TCM syndrome patterns of PSCI by using data mining methods. The findings will shed light on the TCM pathogenesis theory of PSCI, and thus provide translation for optimization of syndrome-targeted treatment strategies of PSCI. Design: This is a registry study-based participant survey conducted in 14 medical centers in eastern China. Mutual information and Markov clustering analysis (MCL) were carried out to achieve syndrome patterns validation of PSCI. Results: Based on MCL, six syndrome patterns were extracted: heart and spleen qi deficiency, liver and kidney yin deficiency, phlegm-turbidity internal obstruction and spleen deficiency, blood stagnation, kidney yang deficiency, and hyperactivity of heart-liver fire (heat). Conclusions: Combination of qi deficiency, yin deficiency, phlegm turbidity, blood stasis, yang deficiency, and fire (heat) may play a key role in PSCI pathogenesis. Treatment strategies by TCM herbal prescriptions should thus be targeted to regulating qi, nourishing yin, resolving turbidity, activating blood, warming yang, clearing fire (heat), regulating kidney, regulating spleen, regulating liver, and regulating heart. Further studies are needed to verify the current findings.