Objective To explore the mediating roles of achievement motivation and knowledge sharing between the growth needs strength and innovation ability of undergraduate nursing interns. Methods A survey was conducted on 213 undergraduate nursing interns from a tertiary hospital in Hubei Province by the general information questionnaire,the Growth-need Strength,the Achievement Motive Scale,the Knowledge Sharing Scale,and the Innovation Capability Scale. A structural equation model was constructed using Mplus 8.0 to analyze the relationship between the growth needs strength,achievement motivation,knowledge sharing behavior,and innovation capatility of nursing students. Results The intensity of growth needs strength of students was scored as（29.40±3.41）,achievement motivation was scored as（7.20±1.80）,knowledge sharing was scored as（42.34±5.28）,and innovation capability was scored as（35.90±4.55）. There were positive correlations among the four（P<0.001）. The mediation model revealed that the direct effect of growth needs strength on innovativeness was significant（β=0.323,P<0.001）. Besides,growth needs strength could also affect innovativeness through three pathways：the independent mediating effect of achievement motivation（β=0.109,P=0.007）,the independent mediating effect of knowledge sharing（β=0.197,P<0.001）,and the chain mediating effect of achievement motivation and knowledge sharing（β=0.022,P=0.008）,with the mediating effects accounting for 50.38% of the total effects. Conclusion Achievement motivation and knowledge sharing play a mediating role between undergraduate nursing interns’ growth needs strength and innovation capability,and their innovation capability can be improved by guiding undergraduate nursing interns’ achievement motivation and providing knowledge sharing conditions.