The invention relates to a hydrogen self-supply type photoinitiator and a preparation method of the hydrogen self-supply type photoinitiator. The hydrogen self-supply type photoinitiator is a compound having a structure of Formula (I) as below, wherein L represents core framework structure of n function, and is independently selected from hydroxyl-containing small molecular compound or residual base of polyether; m and n represent integers 1-6 independently, and n is not more than m; PI is photosensitive radical group, and selected from thioxathone or substituted thioxathone radial group; R is selected from H, linear chain or branch chain C1-C18 alkyl, phenyl, substituted phenyl, benzyl or substituted benzyl as the (III), (IV), (V), (VI), (VII) structures of the Formula below: FORMULA. The photoinitiator can be the hydrogen self-supply type, and can efficiently initiate light polymerization reaction under the condition of not adding initiator, and avoid the shortcomings of volatile, migration and odor of assistant initiator. The preparation method directly introduces the ester exchange radical group through the direct reaction between methyl chloroacetate and thioxathone carboxylic acid, and overcomes the environment pollution caused by using thioxathone acyl chloride in ordinary method; the synthetic process is green and environment-friendly, and the reaction condition is relatively gentle. The FORMULA (I) is as shown in the description.