The invention relates to the field of laser annealing, and discloses a laser annealing device, a production process of a polycrystalline silicon thin film, and a polycrystalline silicon thin film produced by the same. The laser annealing device comprises an annealing chamber, in which a laser generator is provided, wherein an annealing window, through which the laser passes, and two light-cutting plates oppositely provided above the annealing window are also provided in the annealing chamber, wherein the light-cutting end face of each of the light-cutting plates is a wedge-shaped end face. In technical solutions of the invention, since the light-cutting end face is a wedge-shaped end face, the included angle formed by the reflected beam, which is formed by the reflection of the incident beam arriving at the light-cutting end face, and the ingoing beam, which passes through the annealing window, is relatively large, and the vibrating directions of them differ relatively greatly. Hence, the phenomenon of interference will hardly occur, and thus the interference mura generated on the polycrystalline silicon thin film due to the interference is reduced, the quality of the polycrystalline silicon thin film is improved, and the percent of pass of the product is also increased.