The novel multi-target antibodies to a group of compounds were designed and induced for the immuno-enrichement process.Compared with the normal antibodies which is specified to one compound, the antigen used for the multi-target antibody was designed for a relative common structure of a series of compounds.For example, the Estradiol-17-HS was used to prepare the complete antigen due to its relatively long carbon chain with a reactive carboxyl group on the end.The conjugation took place between the amino group of BSA and the carboxyl group of E2-17-HS, allowing the structure of interest to be favorably exposed.The purpose of the study was to produce a kind of polyclonal antibody with the specific selectivity towards three naturally occurring estrogens.