Abstract: In the trial,ovocyte of cattle was used as material and trichostatin-A was used as suppressor of de-acetylase.The intensity of Acetylization of histone H4K12 was determined by laser confocal microscopy technique to explore the activity of transacetylase（HAT） and histon de-acylase（HDAC） during reduction division phase of Ⅰand Ⅱ,the treatment concentration of TSA was 80 μmol/L.The result indicated that fluorescence intensity of histone H4K12 couldn＇t be detected during reduction division phase,and it could be detected from matured ovocytes under the culture condition of TSA,but histone H4K12 disappear completely after the ovocytes were transferred into free-TSA culture medium for 3 hour later.The conclusion could be made that there isn＇t activity to HAT,but HDAC was activity during reduction division phase of Ⅰand Ⅱ.