Abstract: In order to study the relationship between the structure of A-nor-5α-androstanederivatives and their antifertility activity , we designed and synthesized 16 A-nor-5α- androstanecompounds through several reaction steps with dehydroepiandrosterone acetate as a starting material .Their structures were confirmed by IR, ¹HNMR ,MS ,elemental analyses ,etc. Preliminary pharmacological tests showed that compounds 8,9,10 and 16 possess antiimplanta-tion activity to some extent(2.5 mg·kr^-1 ,administered po, gave 67～75% antiimplantationrate).Other compounds showed low activity. The possible relationship between compound structures and their activities is analysed briefly.