Objective To evaluate the physical protective effect of carbomer obstetric gel (COG) on the birth channel in vivo and in vitro experiments by constructing a simulated delivery model in SD rats and Beagles in the form of inserting a catheter balloon into the birth channel and applying external force. Methods Animals were grouped according to their body mass. The non- pregnant SD rats in the in vivo experiment were divided into control (R-C) group, negative control (R-NC) group, medical liquid paraffin (MLP) (R-MLP) group, COG low-dose and high-dose (R-COG-L, R-COG-H) group, in vitro experiment were divided into control (UR-C) group, MLP (URMLP) group, COG low-dose and high-dose (UR-COG-L, UR-COG-H) group. The non-pregnant Beagle dogs in vivo experiment were divided into control (D-C) group, MLP (D-MLP) group, COG low-dose and high-dose (D-COG-L,D-COG-H) group, in vitro experiments were divided into control(UD-C)group, MLP (UD-MLP) group, COG lowdose and high-dose (UD-COG-L, UD-COG-H) group. The pregnant SD rats in the in vitro experiment were divided into control group (P-C group), MLP group (P-MLP group), COG high-dose groups (P-COG-H group). The each control group and negative control group were not administered, each MLP group were given medical liquid paraffin,COG low-dose and high-dose groups were given low and high doses COG. In the in vivo experiment, catheters were inserted into the birth canal of all animals after drug administration. Except for the control group, a certain volume of saline was injected into the catheter balloon of the other groups, and external force was gradually applied until the balloon just came out of the body. Hematoxylin-eosin (HE) staining was used to detect the extent of impairment of the birth canal tissue. In the in vitro experiment, birth canals in vitro were used to investigate the maximum percentage of smooth muscle stretchability (L d / L₀ ). Results The result of in vivo experiments showed that, compared with RMLP group, the external force required for balloon release in the birth canal was significantly lower in R-COG-L and R-COG-H group in non-pregnant SD rats ( P < 0. 001 ), compared with the R-C group, the lesions at the administration sites in the R-COG-H group were significantly milder, while no significant differences were observed in the lesions at the administration sites of the other two groups. The in vivo test result of non-pregnant Beagle dogs showed that compared with the D-MLP group, the external force required for balloon prolapse in the birth canal in the D-COG-L group and the D-COG-H group was significantly reduced ( P < 0. 05). The degree of injury and the incidence of lesions in the D-COG-L group and the D-COG-H group of Beagle dogs were both reduced by concentration correlation. The result of in vitro experiments in non-pregnant Beagle dogs, pregnant SD rats and non-pregnant SD rats all indicated that compared with MLP, COG could effectively increase the extensibility of isolated smooth muscle, and there was a dose-positive correlation. Conclusions Successfully constructed simulated delivery models for SD rats and Beagle dogs, COG demonstrated labor facilitation during the delivery process in SD rats and Beagle dogs, with better efficacy than MLP.