In order to get a Vietnam business visa, you must meet the following requirements:
You are not prohibited from entering Vietnam.
You must have a sponsor company in Vietnam (the company you will work for after entering Vietnam) that is willing to sponsor your visa and travel. It must be a real company, not a service one, as you may encounter certain hardships if using a service/ghost one.
Your passport must be valid for at least 6 months from your date of entry into Vietnam and have at least 02 blank pages.
Your portrait photos (4*6cm, or 2*2 inch, white background, in paper or .jpg, depending on your way of Vietnam business visa application).