The first flowering time,changes of plant height,crown diameter,leaf number and branch number of cut flower,Callistephus chinensis ‘Day Light’,were recorded by separately cultivating it under long days and short days.Results showed that no leaf number difference was found between ‘Day Light’ grown under long days and short days.It tends to have an upright habit with increase in height but decreases in crown diameter and branch number under long days suitable for cut flowers; Flowering of ‘Day Light’ was promoted by short days and was a quantitative short day plant.It was suggested that ‘Day Light’ be cultivated under long days at vegetative stage to develop the high plant type for cut flowers,and then under short days to flower fast.