Objective To investigate the application of low tube voltage CT angiography in the preoperative examination of children with cardiovascular malformation. Methods A total of 82 children with cardiovascular malformation who underwent CT angiography from April 2018 to April 2019 were selected and divided into a control group and an observation group according to age and gender. Both scanned at a fixed current of 150mA, the 40 patients in the control group were given a voltage of 120 kV, and the 42 patients in the observation group were given a voltage of 90 kV. The excellent rate of images, signal-to-noise ratio （SNR）, contrast-to-noise ratio （CNR）, signal strength of target tissue, and background noise, as well as CT dose index volume （CTDIvol）, dose-length product （DLP）, and effective dose （ED） between the two groups were compared. Results There were no significant differences between the two groups in the excellent rate of images, SNR, and CNR （P>0.05）. The signal strength of target tissue and background noise in the observation group were significantly higher than those in the control group, and the CTDIvol, DLP, and ED were significantly lower （P<0.05）. Conclusion Low tube voltage CT angiography applied in the preoperative examination of children with cardiovascular malformation can decrease radiation dose and have a less effect on image quality; therefore, it is worthy of clinical promotion and application.