BACKGROUND The appropriate nurse staffing reflects the situation of nursing management of human resources. Nurse managers have a pivotal role in determining a competent and sufficient number of nurses. It is important to understand the factors influencing nurse staffing to promote appropriate staffing levels. The study aimed to explore the factors affecting nurse staffing from the perspective of nursing managers. METHODS Purposive sampling was adopted to recruit 14 nurse managers from secondary and tertiary hospitals located in the central region of China, and semi-structured interviews via telephone were conducted from April to May 2022. Interview transcripts were analyzed and collated using thematic analysis. RESULTS This research identified four themes and ten subthemes influencing nurse staffing. Extracted themes include: government level (inadequacy of mandatory policies, budgetary constraints), hospital level (hospital characteristics, the control of nurse labor costs, inadequate support on nursing), patient level (patient characteristics, increasing care needs), and nurse level (nurse shortage, skill-mix, individual high-level needs). CONCLUSIONS The findings indicate that it is crucial for decision-makers or policymakers to legislate for safe nurse staffing and establish effective supervision and funding incentives. Tailored interventions are also needed to improve the organizational context, address the nurse workforce and balance the structure of nurse staff.