Abstract: Taking cultured large yellow croaker as the reasearch object,the effects of ultrahigh pressure (UHP) treatment on the actin characteristics of cultured large yellow croaker were studied.The effects of different pressure (300,350,400 MPa) and holding time (3,6,9 min) on calcium ion ATPase,surface hydrophobicity,active sparse group content,thermal stability and SDS-PAGE electrophoresis of actin in cultured Pseudosciaena crocea were studied. The results showed that ultra-high pressure could lead to the increase of surface hydrophobicity,the increase of active sulfhydryl content,the decrease of protein molecular weight and the change of structure of actin in large yellow croaker with the increase of pressure and holding time.The value of the denaturation and denaturation of the protein thermal denaturation decreased with the increase of the pressure holding time,and the activity of the calcium ion ATPase decreased with the increase of the time of the whole of 400 MPa,and the concomitant time of 300 MPa and 350 MPa was first increased and then decreased.The results showed that actin was affected by ultrahigh pressure and had a significant effect,which would lead to the aggregation or breakage of protein structure,and then affect the biochemical characteristics.