Objective: To explore the significance of ultrasound and ultrasound-guided coarse needle biopsy in the clinical diagnosis of breast cancer patients in pregnancy. Methods: A total of 10 patients with breast cancer in pregnancy were selected to study from October 2018 to October 2019 in our hospital, who were given preoperative ultrasound results and ultrasound-guided coarse-needle biopsy histopathology, and the results were analyzed. Results: All the 10 patients showed thickening of the mammary gland body, appeared to pick up disorderly situation, most of the dilated catheter, including 8 patients with solid hypoechoic mass, irregular shape, and "crab foot" edge burr. The corresponding aspect ratio value was greater than 1. The other 2 patients presented with cystic mixed masses with poor boundary definition, irregular shape, and mostly accompanied by posterior echo enhancement. Conclusion: Simple ultrasound diagnosis for patients with breast cancer during pregnancy has some errors, and should be used in combination with ultrasound-guided coarse needle biopsy operation. This method has a high clinical diagnosis rate and significant clinical application value, so it is worth promoting.