The invention discloses a self Raman yellow light laser of a composite cavity structure. A laser diode pumping source emits pump light in an absorption belt of a gain medium, the pump light is focused inside the gain medium through a transmitting energy fiber and a coupling lens set, the gain medium absorbs the pump light to form population inversion, and base frequency laser generation is formed under the feedback action of a laser resonant cavity composed of a resonant cavity shared reflector and a laser total reflector; when base frequency laser passes through the gain medium, Raman gains are generated, and after the Raman gains are greater than the cavity loss of a Raman resonant cavity composed of the resonant cavity shared reflector, a beam splitter and a yellow light output mirror, stable Stokes light generation is formed in the Raman resonant cavity; the frequency of Stokes light is doubled in a frequency doubling crystal, and the generated yellow light secondary harmonic wave is output by the yellow light output mirror. The composite cavity structure is adopted, the length of a base frequency laser resonant cavity is largely decreased, and therefore the stable area of the resonant cavity is effectively enlarged, and the effect of improving the output power of the self Raman yellow light laser is achieved by applying higher pumping power.