Objective To compare the effects of modified long‑axis in‑plane (MLAX‑IP) and dynamic needle tip positioning (DNTP) on femoral artery catheterization in infants with congenital heart disease. Methods A total of 80 infants with congenital heart disease, American Society of Anesthesiologists (ASA) Ⅱ or Ⅲ, boys or girls, age 1 day‒6 months, and weighting 2.8‒8.0 kg were enrolled. According to the random number table method, they were divided into two groups (n=40): a MLAX‑IP group and a DNTP group. Femoral arterial catheterization was performed using MLAZ‑IP or DNTP. Both groups were compared for femoral arterial catheterization procedures (including first‑attempt success rate, imaging time, and total puncture time) and complications (including posterior artery wall puncture, infection and embolism). Results The first‑attempt success rate was higher in the MLAX‑IP group than that in the DNTP group (P<0.05). The imaging time in the MLAX‑IP group was longer than that in the DNTP group (P<0.05). However, there was no statistical difference in total puncture time between the two groups (P>0.05). Compared with the DNTP group, the incidence of posterior artery wall puncture decreased in the MLAX‑IP group (P<0.05). No infection or embolism occurred in either group. Conclusions During femoral artery catheterization in infants, the success rate of catheterization with the MLAX‑IP is higher than DNTP. The incidence of posterior artery wall puncture is low, without increases in the total puncture time.