Considering the deviation in the time-of-flight of synthetic aperture sequential beamforming (SASB), which causes serious artifacts, this study proposed an endoscopic ultrasound-imaging algorithm (SASB-MV) combining the linear constrained minimum variance (MV) criterion with the SASB algorithm. The algorithm first focused on each virtual source point, obtained the ultrasonic echo signal vector of the imaging point, and constructed the sample covariance matrix based on the ultrasonic echo signal vector of the imaging point. The algorithm then constructed the weight vector based on the linear constraint MV criterion and finally obtained the high-resolution echo signal value of the imaging point through the weight and ultrasonic echo signal vectors. Moreover, this study conducted simulation experiments of scattering point and circular dark spot in Filed II. Experimental results show that compared with the dynamic receive focusing (DRF) and SASB algorithms, the lateral resolution of the proposed algorithm improved by 59.1% and 31.2%, and the contrast improved by 44.68% and 16.23%, respectively.