Carbon dots (C-dots) enfolded by Ribonuclease A (RNase A) on the surface were synthesized via a one-step microwave-assisted method.By simply adjusting the reaction time, C-dots with different fluorescent color have been successfully synthesized.The as-prepared C-dots emit strong florescence upon UV-light excitation without further passivation and the quantum yield of the C-dots can reach as high as 24.20%.