Aim To study the effect of calcitriol for leukoaraiosis（LA） patients with mild cognitive impairment（MCI）. Methods 256 patients with LA, 181 patients with MCI were selected according to the diagnosis of MCI, and divided into two groups: control group （85 cases）, intervention group （88 cases）. Calcitriol 0.25 μg/day was used in intervention group, other treatments and rehabilitation treatment were the same in two groups. Observation period to two groups was 12 months. And cognitive function was test by montreal cognitive assessment （MoCA） score before include and 6 months and 12 months before and after treatment. The changes of cognitive function were comparatively analysed before and after treatment between the two groups. Results （1） 181 cases were diagnosed as MCI （70.70%） in 256 patients with LA, which were randomly divided into control group and intervention group, and got follow-up of 12 months 173 cases were into the statistics eventually, 85 cases in control group, 88 cases in intervention group All the patients into research had not appeared severe adverse reactions. （2） The delayed memory score was the lowest in two groups, and abstract feature, visual space and executive function were reduced significantly. MoCA score improvement was not obvious in intervention group at 6th month （19.23±2.42）, but the score increased from 18.84±2.08 before treatment to 22.32±2.36 at 12th month （P<0.01）, when the scores between two groups were different significantly （P<0.01）. The score of language increased in intervention group at 6th month, 12th month （2.37±0.86, 2.52±0.86）, compared with that of before intervention（1.84±0.73, P<0.01）. And at the two points, the language scores in intervention group were also different significantly compared with control group. For delayed memory, there were no obvious improvement in intervention group at 6th month （1.35+1.37）, but the score increased at 12th month （2.77±1.84） compared with that before intervention （1.30±1.41, P<0.01）. At 12th month the delayed memory scores were significantly different between two groups （1.41±1.46 vs 2.77±1.84, P<0.01）. The abstract function, visual space and executive function score in two groups had no significant change at each time point （P>0.05）. Conclusions The calcitriol was effective on MCI correlation with LA, but the work was slow. The language ability improved faster, and delay memory function needed a long treatment cycle. It had a certain limitation for calcitriol to improve the abstract function, visual space and executive function.