Abstract: Taking drinking water in Hohhot area as the research object,using the means of risk assessment,The hazard identification,hazard description, exposure assessment and risk description,four aspects of nitrate in water hazard factor were described to carry on the scientific evaluation,determine the risk quotient （HQ） was 34.4%.Nitrate subacute toxicological experiment was carried out at the same time,the results showed that： based on the dietary exposure to low dose group,alkaline phosphatase （ALKP）,lactate dehydrogenase （LDH）,aspartate aminotransferase （AST）,UREA （UREA） was higher than the control group, and extremely significant difference （P<0.01）;Based on the dietary exposure to high levels of drug group,globulin （GLOB）, lactate dehydrogenase （LDH）,aspartate aminotransferase （AST）,alanine aminotransferase （ALT）,blood phosphorus （P）,UREA （UREA） was higher than the control group, and extremely significant difference （P<0.01）.