The invention discloses an optical communication system using grounded coplanar waveguide, comprising a current buffer and a transimpedance amplifier (TIA). Transmission lines of the optical communication system have grounded coplanar waveguide (GCPW) structures. The current buffer receives a current signal from a signal source, and outputs the current signal after reducing capacitance effects of the signal source. The TIA converts the current signal to a voltage signal, wherein a first end of the TIA receives the current signal, a second end of the TIAn outputs the voltage signal, and a shunt-shunt feedback circuit is coupled between the first end and the second end. Therefore, the present invention can minimize the circuit area and lower the power consumption as well.