The invention relates to a high-surface gloss glass fiber reinforced flame retardant polycarbonate composition and a preparation method thereof. The composition comprises the following components by weight parts: 50-95 parts of polycarbonate, 5-50 parts of glass fiber, 0.1-5 parts of surface modifier, 0.01-0.2 part of flame retardant agent and 0.05-2 parts of anti-dripping agents. The preparationmethod comprises the steps of: adding the polycarbonate, the surface modifier, the flame retardant agent and the anti-dripping agents in a high-speed mixer in the proportions; stirring and mixing in uniformity; delivering the mixture in a twin-screw extruder through a main feeder; adding the glass fiber in the extruder through a side feeder; extruding and cutting into grains to obtain the high-surface gloss glass fiber reinforced flame retardant polycarbonate composition. Compared with the prior art, the high-surface gloss glass fiber reinforced flame retardant polycarbonate composition has the characteristics of high surface gloss, high rigidity, no welding line, no fogging, and the like. The high-surface gloss glass fiber reinforced flame retardant polycarbonate composition can be directly used as a structure and appearance integrated component, and can be used as a component integrating a face frame, a base and an inner structure of a display.