The invention discloses a distributed fiber Raman/Brillouin scattering sensor which comprises a semiconductor FP cavity pulse broadband fiber laser, a semiconductor outer cavity narrowband continuous fiber laser, a wave separator, an electrooptical modulator, an isolator, am erbium-doped fiber amplifier, a bidirectional coupler, an integrated wavelength division multiplexer, two photoelectric receiver and amplifier modules, a direct detection system, a narrowband transmission fiber grating, a circulator and a coherent detection system. On the basis of the fiber nonlinear optical scattering fusion principle and the wavelength division multiplexing principle, the sensor detects the fiber temperature by using the ratio of back fiber spontaneous anti-stokes and stokes Raman scattering light intensity. And the fiber strain is measured by the frequency shift of the back fiber spontaneous Brillouin scattering light, thereby simultaneously measuring temperature and strain, increasing the signal-to-noise ratio of the system and enhancing the measurement accuracy.