The invention provides a polycarbonate composition and a preparation method thereof. The polycarbonate composition comprises the following components in parts by weight: 50-90 parts of polycarbonate,5-50 parts of an acetone-treated fibrous filler, 0.1-3 parts of a silicone oil dispersant, 0.05-0.2 part of a lubricant and 0.01 -10 parts of other auxiliary agents. The content of bisphenol A in thepolycarbonate is between 0 and 50 ppm, and the content of hydroxyl in the polycarbonate is between 20 ppm and 300 ppm. The lubricant is one selected from oxidized polyethylene wax lubricants, ethyleneacrylic acid copolymer lubricants, polyethylene wax lubricants and high-acid-value polyethylene wax lubricants. According to the polycarbonate composition disclosed by the invention, through collaborative use of the acetone-treated fibrous filler, the silicone oil dispersant and the lubricant, the surface energy of the material can be reduced, and toughness of the material can be improved.