This research explores various factors influencing the implementation of Environmental Cost Management Accounting (ECMA) in Vietnamese manufacturing industry, including coercive pressure, normative pressure, simulation pressure, managers’ perception of environmental uncertainty, and proactive environmental strategy. A mix-study method has been applied in two stages to achieve the research aims. First, the qualitative method was conducted using the expert interview tool to assess factors affecting ECMA application at Vietnam to examine, screen, and determine the relationship between variables in the theoretical model, on that basis to propose research model. To achieve the objectives above, 18 in-depth interviews are conducted by semi-structured interview method with experienced researchers, lecturers of universities, financial directors, accounting staff at businesses, a number of financial accounting experts. At 2nd stage, the qualitative method has been applied by surveying 151 individuals in this industry from three groups: (i) business managers, (ii) accountants or management accounting staff, and (iii) production, technical, and environmental department staff or supervisors in manufacturing companies (MEs). Through the empirical analysis, the findings indicate that the adoption of ECMA remains relatively low, primarily influenced by coercive pressure and managers’ perception, while the impact of normative pressure appears uncertain, and proactive environmental strategy has no discernible effect. The research also comments and clarifies the relationship between the factors (1) Coercive pressure, (2) Simulation pressure and (3) Manager’s perception of the environmental uncertainty and the application of ECMA at MEs. Based on these results, the recommendations for guiding the implementation of ECMA are given in Vietnam manufacturing enterprises.