Background Radial artery cannulation is a crucial investigative procedure for measuring patients’ blood pressure invasively and serial blood gases. However, radial artery cannulation can be challenging for medical residents, and it is necessary to establish a facile and straightforward teaching strategy. This study aimed to evaluate the efficiency of acoustic shadowing-facilitated ultrasound guidance on radial artery cannulation teaching for medical residents. Methods A total of 116 medical postgraduates who underwent standardized residency training programs in the Department of Anesthesiology were randomly divided into a new ultrasound-guided teaching group and a traditional ultrasound-guided teaching group. In the new ultrasound-guided teaching group, radial artery puncture technique was taught by acoustic shadowing-facilitated ultrasound guidance. The training included both theoretical and practical components. After the training, the success rate of the first puncture attempt, the success rate of the catheterization, the ultrasonic positioning time, and the catheterization time of the two groups were compared in a unified manner. A questionnaire on the subjective evaluation of the various aspects of the program by participants was conducted at the end of the training period. Results The study included 101 medical residents. The success rate for radial artery puncture at the first attempt in the new ultrasound-guided teaching group was 78.43%. It was significantly higher than that of the traditional ultrasound-guided group (58.00%, odds ratio = 0.380; 95% CI = 0.159 to 0.908; p = 0.027). The success rate for the first arterial catheterization in the new ultrasound-guided teaching group was significantly higher than that of the traditional ultrasound-guided group (74.51% vs. 52.00%, odds ratio = 0.371; 95% CI = 0.160 to 0.858; p = 0.019). The ultrasonic positioning time and catheterization time in minutes in the new ultrasound-guided teaching group were significantly shorter than that of the traditional ultrasound-guided group (14.36 ± 3.31 vs. 18.02 ± 4.95, p < 0.001; 10.43 ± 2.38 vs. 14.78 ± 8.02, p = 0.012). However, no significant differences were observed in the incidence of local hematomas and teaching satisfaction scores between the two groups. Conclusion Acoustic shadowing facilitates ultrasound-guided radial artery puncture and catheterization is beneficial in the standardized training and teaching of residents. It improves the success rate of the first attempt at radial artery puncture and catheterization and shortens the time of ultrasound location and catheterization. Trial registration Registered in the Chinese Clinical Trial Registry on 28 May 2021. Registration number: ChiCTR2100046833.