The present invention provides a photocurable composition prepared using mercapto benzophenone compounds as key raw materials. The present invention aims to solve the problems existing in the prior photo-curing technology that low-molecular photoinitiators are easy to remain and migrate, while macromolecular photoinitiators has low initiation efficiency due to a low content of effective components and also has the problem of certain migration. The photocurable composition in the present invention can be easily prepared and has high addition efficiency with ethylenically unsaturated compounds, and the photocurable composition obtained by addition has no residual mercapto and has features of high initiation activity and zero migration rates when it is used in photocurable coatings, binder and ink formula.