Risk assessment is the key component of risk analysis together with risk management and risk communication. FAO/WHO encourages member states to used risk assessment as the basis of their national food standard development, in order to harmonize national standards and avoid trade dispute. Risk assessment is comprised of hazard identification, hazard characterization, intake assessment and risk characterization. The major outcome of risk assessment of chemical hazards is the development of tolerable intake levels, such as, Acceptable Daily Intake (ADI), Provisional Tolerable Weekly Intake (PTWI), etc. These outcomes could be applied to all populations in different geographical areas in the world. On the other hand, the outcome of intake assessment could not be applied universally, so each country should conduct intake assessment in the development of national standards. For carcinogens without threshold, the outcome of risk assessment is presented as potency and population risk. Recently, microbial risk assessment (RMRA) is being conducted internationally, i.e. to study the dose-response relationship in food borne disease and estimate the amount of microorganisms that could cause 50% of the consumers developing disease. In China, risk assessment is being used routinely in food safety standard development, especially in standards related to chemical contaminants. However, further improvements are needed as compared with the risk assessment practice in the developed countries.