Two photocleavage polysiloxane-based macromolecular photoinitiators, NH2-2959-2 and NH2-2959-4, were synthesized with 2-hydroxy-4'-(2-hydroxyethoxy)-2-methyl-propiophe (2959) and amino polysiloxane as raw materials. The properties of UV/vis absorption and degradation, photopolymerizetion and self-floating ability of the photoinitiaors were investigated. The results show that both of the photoinitaitors have a similar maximum absorption peak at 275 nm, and the intensity of the UV/vis absorption peak tended to decrease against the increase of the UV ir-radiation time. The system containing NH2-2959-4 exhibited a higher photopolymerization rate than that of NH2-2959-2. Compared with 2959, the NH2-2959-2 and NH2-2959-4 both possessed good self-floating ability, and could spontaneously migrate to the surface of the system to form a concentration gradient.Cited