Transmission of CATV with optical cables instead of electrical cables is the trend in the days to come. The main problems that we are taking notice of after electrical cables being replaced with optical cables are discussed. The concerned equation of Carrier-to-Noise Ratio （CNR） and the number of possibly achievable channels and PIN/FET’s parameters are found out and the concept of PIN/FET’s integrated evaluation parameter is put forward. Beside the selectable 3 signal combination results that produce no mutual modulation products in every VHF channel are programmed and calculated with computer.