In this paper, the simulative analysis of 8 channels TDM-PON system has been carried out by using NRZ and RZ modulation formats for downstream signals. The performance of TDM-PON system has been evaluated by varying input Pin (0 - 25) dBm for both modulation formats at a constant bit rate of 622Mbps.It has been observed that the TDM-PON system gives the optimum performance at power 20dBm and it is found that RZ is superior to NRZ. The transmission performance characteristic of TDM-PON for both the modulation formats has been evaluated in terms of Q-factor and BER. The System shows the repeaterless transmission up to the distance of 130 km.