[Objective] The study aimed to establish an approach to high titer Et immune serum preparation by low-aged Japanese rabbits. [Method] Antigen of Et was prepared at first, Japanese rabbits were taken as immunized animal, and divided into two groups for experiments, one is two-month-old group （T group）, and another is six-month-old group （S group）. Japanese rabbits were continuous by immunized with low-dose by using auricular intravenous method, then immune sera were collected. Immune serum antibody titer was determined with micro-agglutination reaction method. E Resultl Agglutination reaction showed that the Et serum titer of S group is higher than that of T group in the first testing with the same dose. But in the second testing, the serum titer of the T group and and the S group was consistent, [Conclusien] The animals in the T group （Japanese rabbits） were fewer months old, and produced high titer antiserum was which consistent with the S group, which indicated that the method of preparing of high titer Et immune serum by low-aged Japanese rabbits was feasible.
