The invention discloses a distributed optical fiber Raman temperature sensor coding and decoding by adopting sequential pulses, which is a distributed optical fiber temperature measuring system coding and decoding a signal on the basis of S-matrix transformation and carrying out optical fiber on-line positioning temperature measurement by utilizing the effect of optical fiber Raman light intensity modulated by temperature and an optical time domain reflection principle. The distributed optical fiber Raman temperature sensor can obtain better signal-to-noise radio under the condition of spending same measuring time by using a sequential multidigit laser pulse coding and decoding technology, increase the number of emitted photons, enhance the space resolution by narrowing the thicknesses oflaser pulses and also effectively prevent the nonlinear effect of optical fibers by lowering the requirements on the peak value power of a single laser pulse; and in addition, the invention effectively solves the contradiction of space resolution enhancement-signal-to-noise radio reduction and signal-to-noise radio enhancement-space resolution reduction or measuring time increase of the traditional optical fiber distribution temperature sensor, enhances the temperature measuring precision, can be used for a distributed optical fiber temperature sensor which has ultra long range and high spaceresolution.