This study aimed to explore the in-service training needs and expectations of junior nurses in Chinese emergency departments, using the Capability-Opportunity-Motivation-Behaviour (COM-B) model to inform the development of targeted training strategies.A qualitative descriptive design and inductive thematic analysis were used. Semi-structured face-to-face interviews were conducted with 16 emergency department (ED) staff between January and February 2025.The training needs and expectations of junior ED nurses can be summarised into four themes: capability, the depth of mental and physical needs; opportunity, the two-way construction of physical and social opportunities; motivation, the synergy of self-motivation and reflective motivation; and training management: diversified training forms, scientifically reasonable training time, composite team of lecturers, and multidimensional assessment and evaluation.In developing in-service training program, nursing managers should pay attention to the needs of nurses in terms of competence, motivation, opportunity and training management, and design training content and forms that meet actual needs, in order to enhance the professionalism and clinical competence of junior ED nurses, strengthen professional identity and work motivation, reduce the willingness to leave, and promote sustainable development.Copyright © 2025 The Authors. Published by Elsevier Ltd.. All rights reserved.