Administrative manager training and development in universities as a contribution to effective university administration in the context of strong movement to autonomy in higher education is a matter of deep concern for many university leaders nowadays. Recognizing the influencing factors and their levels of impact on training and developing administrative managers could allow university leaders to implement appropriate and effective solutions for the process of training and development. This article presents the results of research into the factors affecting middle administrative manager training and development at member universities of Vietnam National University Ho Chi Minh City through surveying opinions of 484 individuals who were officials and managers working at 07 member universities of Vietnam National University Ho Chi Minh City, and further interviewing 07 participants. 03 categories of factors with 19 items identified as having an impact on middle administrative manager training and development, ranked from high to low level of impact, were organizational factors, functional factors and individual factors. More importantly, the results indicate that factors related to humans, including support from university leaders, capabilities of staff responsible for middle administrative manager development, and motivation of middle administrative managers, are identified as having the greatest impact on training and developing middle administrative managers.