In order to determine the basic causes of major accidents which may occur in the reforming unit, and take the countermeasures of safety, this paper used the risk degree assessment method for safety assessment about the reforming unit. Hidden danger of the unit was found by the analysis of risk, and intrinsic risk grades of the equipment units was divided by the risk assessment table. Results show that the unit has very high intrinsic risk grade, in which the existence of a large number of hazardous substances, most equipments because of the high temperature and pressure, corrosion and other factors can easily lead to the leakage of medium, so as to cause fire and explosion. According to the results of the assessment, propose the corresponding safety measures to prevent accidents, ensure the production running smoothly.