This study aims to identify and evaluate the influence of the factors affecting the implementation of occupational health and safety of employees and employers and its impact on occupational health and safety and legalize risk assessment in small and medium-sized manufacturing enterprises in central Vietnam through the survey among 246 business representatives and data processing through the software SPSS 20 and AMOS 20. The results show that there are 3 factors affecting the implementation of occupational health, safety and hygiene. In order: (1) Safety regulations and instructions; (2) Occupational health, safety policy and (3) Occupational health and safety training. There is no relationship between the impacts on the implementation of occupational health and safety of the employer. In addition, a very interesting finding about the relationship of factors implementing occupational health and safety of employers was a positive influence on the legalization of risk assessment activities. On the basis of these results, employees, business owners and state management agencies will have grounds to offer useful solutions in risk assessment in order to better perform safety work and occupational health.