The invention discloses a production technology for producing magnesium oxide through direct reduction of magnesium sulfate. Carbon black, activated carbon or coke is taken as a reducing agent, and the reducing agent and magnesium sulfate are firstly heated to a first temperature and then change between a first temperature and a second temperature for a period of time to obtain magnesium oxide, wherein the ash content in the reducing agent is smaller than 8% (mass), the first temperature is 800-900 DEG C and the second temperature is 1,000-1200 DEG C. The magnesium oxide prepared by the preparation technology is high in purity, the generated residues are extremely few and the treatment cost is relatively low.