The invention discloses PC (polycarbonate) composition, a preparation method thereof and a novel material. The PC composition comprises a PC material, a spinel compound and a melt flow index stabilizer, wherein the melt flow index stabilizer adopts phosphate comprising more than one of zinc phosphate and sodium phosphate. Phosphate is taken as the melt flow index stabilizer, the principle is as follows: phosphate contains phosphorus atoms, the phosphorus atoms and metal ions can form a complex with high thermal stability, and the complex can be dissolved in a polymer PC material and cannot be precipitated out of the material, so that the metal ions are inactivated. Further, PC cannot be degraded through catalysis of the metal ions, and the melt flow index is stabilized. The PC composition cannot be degraded in an injection molding process, splay marks and silver streaks cannot be produced, and the plating performance of the PC composition is good.