A fluorenylaminoketone photoinitiator, a preparation method thereof, and a UV photocurable composition containing same. The photoinitiator has a compound having a structure as shown in general formula (I) or a derivative compound thereof. The fluorenylaminoketone photoinitiator may effectively improve the solubility of traditional photoinitiators and reduce the use of micromolecular active diluents, and may also have high sensitivity and good deep-layer curing. It has very good promotion effect on popularization and application of photocurable compositions, particularly colored ink systems, in the field of photocuring. A UV photocurable composition containing such a fluorenylaminoketone photoinitiator can have an advantage in terms of high sensitivity, no residue after development, good pattern integrity, no or little odor of coating layers after curing, or excellent yellowing resistance.