Objective To investigate the effect of transthoracic echocardiography on locating the catheter tip during totally implantable venous access port (abbreviated as port) implantation in children. Methods The clinical data of 200 patients with malignant tumor who received port implantation in our hospital from Mar. 2015 to Jun. 2020 were retrospectively analyzed. The patients were divided into X-ray positioning group (105 cases) and ultrasound positioning group (95 cases) according to the catheter tip positioning mode. The general information, operation duration, the rate of ideal catheter tip position and postoperative complications of the 2 groups were analyzed. Results There were no significant differences in age, gender, height, weight, body mass index or tumor types between the 2 groups (all P>0.05). The mean operation duration of the X-ray positioning group and ultrasound positioning group was (57.79±6.39) min and (49. 84±4.34) min, with significant differences (P<0.01). The rates of ideal catheter tip position in the X-ray positioning group and ultrasound positioning group were 92.4% (97/105) and 96.8% (92/95), with no significant difference (P=0.167). There were no significant differences in postoperative wound infection rate, catheter-related thrombosis, fibrin sheath formation around catheter, ectopic catheter, catheter-related bloodstream infection or unplanned port removing (all P>0.05). Conclusion Transthoracic echocardiography can directly and accurately monitor the catheter tip position in real-time during venous access port implantation in children, and has the advantages of X-ray irradiation free, short operation duration, simple equipment requirements and convenient operation, making it worthy of clinical application.