Objective To explore the effects of port implantation with ultrasound-guided modified Seldinger puncture technique at the upper arm for breast cancer patients. Methods Totally, 73 patients with breast cancer who needed ports implantation at the upper arm were recruited. Ultrasound guidance combined with modified Seldinger technique was used to assist implantation of ports at the upper arm: after successful puncture, a 0.018-inch diameter guidewire was advanced into the catheter, and then a 5Fr sheath passed through; intravascular electrocardiograph (IVECG) signal was conducted from the guidewire to determine the length of intravascular catheter portion before insertion; then a reservoir (the port chamber) positioned completely beneath the skin, was sutured at the base of port pocket.The length of implantation, rate of successful implantation, and complications occurring imme-diately after implantation were recorded. Results The rate of successful implantation was 95.89%; the length of implantation ranged 15-45（25.46±6.22）min.Pain level was（1.63±0.74） points during implantation, and （2.94±0.67）points after 24 h.Nerve injury occurred in only one case. Conclusion Port implantation with ultrasound-guided modified Seldinger puncture technique could enhance rate of successful implantation, shorten the length of implantation, mitigate patients′ pain levels, and effectively prevent port implantation related complications.