Objective: To study the effect of heart rate change on the quality of 256 slice spiral CT coronary artery imaging.Methods: 3895 cases of suspected or diagnosed coronary heart disease underwent 256 slice spiral CT angiography of coronary artery and randomly selected 489 patients,according to the heart rate were divided into 3 groups: the first group is the heart rate less than or equal to 75 times/min,the heart rate of the second groups was 76~100/min,third groups for heart rate>100 times/min.