The constant growth of the needs for higher speed and capacity of telecommunication networks is dictated by intensive scientific and technological research and development in the field of optical telecommunications. The introduction of new technologies resulted in an increase in the capacity of optical transmission network of about 2.5 times a year. Since the first optical line introduced at the beginning of the sixties with a capacity of a few kbit/s sufficient for one phone line, today's capacity increased to over 10 Tbit/s, which allows more than 250 million simultaneous phone calls, or more than 100 thousand broadband connections flow 10 Mbit/s. In this monograph, the results of modeling and computer simulation of some parameters of the optical network are given. The influence of many parameters on the quality of signal transmission in optical networks was analyzed.