The aim of this study was to validate a modified method of using a laparoscopic compression anastomosis clip (LapCAC) for gastrointestinal anastomosis in an animal experiment and two clinical cases. Anastomotic surgery of the upper digestive tract was performed on dogs using the conventional and modified methods for LapCAC. The animals were sacrificed postoperatively at different time points to obtain sections from the anastomotic site for pathologic study. Anastomotic outcomes of the two methods were also verified in two clinical cases. The animal experiments and the two clinical cases showed that no anastomotic leakage occurred with the modified method, and that the new method was simple, convenient and reliable as compared with the conventional method. The mean time of placing the anastomosis clip was shorter, and the mean numbers of operation attempts, secondary actions and sutures in the operating holes were reduced. The serosa at the anastomosis healed completely, the muscular layer and submucosal fibers proliferated well, and the anastomosis was covered with mucosa within two weeks after the operation. LapCAC offered a better surgical outcome when it was used according to the modified method, where anastomoses formed smoothly and completely within two weeks after the operation.