Abstract: Based on newly acquired seismic data and seismic profiles after processing in recent years,Mesozoic recognition of East China Sea shelf basin was carried out,mainly from4 aspects,namely structural characteristics,seismic refection features,contact relationship and seismic formation velocity.The analysis results indicate the Mesozoic faults were undeveloped while the igneous rocks were well developed,which was the primary characteristic distinctive from that of in Cenozoic.Compared with Cenozoic seismic refection features,Mesozoic ones were less continuous,with low frequency and low energy.There were 2 types of contact relationship be-tween Mesozoic and Cenozoic,namely parallel unconformity and angular unconformity.The difference of seismic formation velocity between Mesozoic and Cenozoic was bigger and the stratums were distributed in south areas,with a wider distribution and bigger thickness,extending in direction of NE and NNE.