The invention relates to a cable ampacity analysis system based on a linear temperature-sensitive technology and a calculation method for cable ampacity. The cable ampacity analysis system comprises a server, as well as a distribution type linear temperature-sensitive system and a cable load detector, which are connected with the server, wherein the distribution type linear temperature-sensitive system is formed by a temperature-sensitive optical cable laid on a cable to be detected, a wavelength-adjustable laser and a light intensity detector, and the wavelength-adjustable laser and the light intensity detector are connected with the temperature-sensitive optical cable. According to the invention, via adding a dynamic time variable, correspondence relationship among cable electric flux, surface temperature of a cable outer protective sleeve, cable environmental temperature and cable heat radiation during the operation of the cable is established, and the temperature of a conductor of the cable is calculated, as a result, the analysis system and the calculation method provide a decision basis for ensuring safe operation of cables in cities and reasonably deploying power transmission capacity, supply a scientific basis to scientific load dispatch, and have import significance.