Objective To analyze the effect of early lip muscle function training nursing on the dental and maxillofacial development in children with mouth breathing. Methods A total of 100 children with the bad habit of mouth breathing admitted to our hospital from December 2022 to December 2023 were selected as the research subjects. According to the random number table method, they were divided into the control group and the observation group, with 50 children in each group. The control group received routine training nursing, and the observation group received early lip muscle function training nursing. The maxillofacial morphology, dental cephalometric indexes and skeletal cephalometric indexes were compared between the two groups. Results After nuring, the nasolabial angle and mentolabial angle in the observation group were smaller than those in the control group (P<0.05). There was no significant difference in the mentocervical angle between the two groups (P >0.05). The values of U1-SN and L1-MP in the observation group were lower than those in the control group (P<0.05). There was no significant difference in OP-FH between the two groups (P>0.05). There were no significant differences in SNA, SNB, ANB and FH-MP between the two groups (P>0.05). Conclusion Early lip muscle training nursing can improve dental and skeletal cephalometric indexes in children with mouth breathing. It is beneficial to alleviating the protrusion of anterior teeth, promoting the dental and maxillofacial development, and optimizing the facial morphology.