In order to work as a trainer in corporate, they must at least have a bachelor's degree. However, due to competition in the bussiness industry, many corporate trainers have masters degrees. Their are a variety if majors that you can study in order to persue this career. It depends mostly on the company you want to work with or will be working with. Mostly depending on what the comapny wants you to have knowledge on, and how well you were to execute a real life training session. Some of the majors that are studied include as follows (disclamer:there can be many more majors/fields as mentioned before it just depends on what the comapny is looking for) human resources, business administration, organizational management, educational psychology, information technology. Like in plently of other bussinesses, even with college education, you must always have experience. So considering getting an internship may be helpful, in being hired during the procress.