Abstract: Haemagglutination (HA) test and haemagglutination inhibition (HI) test are widely-used laboratory methods for determination of antibody levels of Newcastle disease and avian influenza. The method is with lots of advantages such as simple material, easy operating,result decided quickly.It is of significance in protecting the health and reducing culture industry of animals, but the method is affected by many factors,which would lead to the wrong test results.This paper comprehensively analyzes the influence of factors affecting the HA test and HI test,in order to avoid and reduce the effect of disadvantageous fators and enhance the accuracy of the test.

Key words: haemagglutination; haemagglutination inhibition; influencing factors