In this study,in order to explore a new method and formation mechanism of inducing androgenesis haploid,Paramisgurnus dabryanus was treated only by cold-shock without egg inactivation to induce androgenesis haploid,and the early development,chromosome number and cytology observation of embryos were analyzed.Results were as follows:early development of the embryos showed that the hatching rate of the 0 ℃ and 3 ℃ groups was 0.83% and 57.42% respectively,which was significantly different(P<0.05),and all of them showed haploid syndrome.Ploidy idenfication showed that the chromosome number of the 0 ℃ group ranged from 18 to 27,haploid rate was 81.40%,and the chromosome number of the 3 ℃ group ranged from 20 to 30,haploid rate was 68.97%.Cytology observation of the split embryo showed:in the 3 ℃ group,60 min after fertilization,egg nucleus and the second polar body were on the embryo surface,and were about to eliminate together.In conclusion,P.dabryanus androgenesis haploid could be successfully induced when treated at 3 ℃ for 60 min,and the cytology mechnism may be that the nucleus and the second polar body were spawned together.Results of this study not only enriched the theory of fish sex control,but also provided new way for the all-male production.