Estrus synchronized yellow cattle (n=150) were divided into 8 experimental groups immunized with different dosages (0.75, 1.50, 2.25, 3.00 mg per animal) of highly- or lowly-purified inhibin fusion expressing plasmid pcISI and 2 control groups immunized with plasmid pcISI or physiological saline to investigate the effect of purity and dosage on corpus luteum development of yellow cattle immunized with inhibin gene expressing plasmid pcISI. Booster immunization was done 21 d after the primary immunization. The results showed that regardless of the highly- or lowly-purified plasmid immunization. inhibin fusion expressing plasmid in dosage of 2.25 mg per animal showed the best effect on corpus luteum size, which in experimental group with dosage of 2.25 mg per animal was remarkably larger than that in experimental group with dosage of 0.75 mg per animal (P<0.05). Inhibin antibody level is closely related to the development of corpus luteum. Corpus luteum sizes on both sides in inhibin antibody-positive cattle were bigger than those in inhibin antibody-negative ones (P<0.05).