〔Abstract〕 Objective To explore whether the capacity of decision-making under ambiguity in adult patients with moyamoya disease(MMD) is impaired and its association with executive function. Methods Neuropsychological scales were used to measure the executive function of forty-one adult patients with MMD and forty-one healthy controls(HC), The Iowa Gambling Task(IGT) was utilized to study the capacity of decision-making under ambiguity of the two groups. Correlation analysis was performed between the two types of data. Results (1) The total number of favorable choices in the MMD group was significantly lower than that in the HC group, with a statistically significant difference(Z=-2.782,P<0.01), and the total number of unfavorable choices was significantly higher than that of the controls, with a statistically significant difference(Z=-2.782,P<0.01). The results of ANOVA showed that the net residual value of Block4 and Block5 in MMD group was lower than that of Block4 and Block5 in HC group, respectively, and the differences were statistically significant(t=-3.433,P=0.001;t=-5.271,P<0.001), the net residual value of Block1 was higher than that of Block1 in HC group, the difference was statistically significant(t=2.715,P=0.008).(2) Spearman correlation analysis revealed no association between the net score of IGT, the total number of favorable choices, the total number of unfavorable choices, and executive function. Conclusion The capacity of decision-making under ambiguity in adult patients with MMD is impaired possibly, which is not correlated with executive cognition.