In the application of ultrasoundguided minimally invasive interventional surgery, it is difficult to track the surgical needle in real time and accurately only using ultrasound images. In this paper, the electromagnetic positioning system combined with ultrasound image is used to realize the task of puncture navigation for minimally invasive interventional robot. The ultrasound image is used to determine the position of the local suspicious lesion area, while the electromagnetic positioning system is used to perform the real time positioning and tracking of the surgical needle. In order to combine them organically, an error compensation method based on Bernstein polynomial is proposed to compensate the tracking error. The Nline model method is used to calibrate the ultrasound image. On this basis, the registration of the surgical needle and the image space is completed, the concept of virtual needle insertion path is proposed, and then the fusion of electromagnetic positioning data and image data is realized. In order to verify the effectiveness and feasibility of the proposed method, the experimental study on the combination of ultrasonic system and electromagnetic positioning system was carried out. A prostate minimally invasive interventional robot platform was built, and the targeted puncture positioning experiments were carried out from various angles. The experiment results show that under the premise of using nylon as robot body material and titanium alloy surgical needle, using this method, the average precision of prosthesis puncture is 114 mm and the average accuracy is 162 mm, which can meet the clinical accuracy requirement of prostate interventional surgery.