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Zircon (≤44 μm) and carbon black (≤30 μm) were used as starting materials and mixed for 24 h using anhydrous ethanol as medium with the mass ratio of 10040, dried fully at 60 ℃ and then dry mixed for 10 h. Specimens with size of 20 mm×5 mm were pressed under 60 MPa, then dried fully at 120 ℃, put into a furnace with 1.0 L·min-1 nitrogen gas and fired at 1 400, 1 450, 1 480 and 1 500 ℃ for 6, 9 and 12 h, respectively. The phase composition and microstructure of the specimens were studied by XRD and SEM, and the carbothermal reduction and nitridation reaction process was thermodynamically analyzed. The results show that using zircon and carbon black as starting materials, ZrN-Si3N4 composite is synthesized by carbothermal reduction and nitridation reaction in nitrogen atmosphere. The composites with different compositions are obtained by controlling the firing temperature and partial pressure of CO gas. The proper firing temperature and holding time to synthesize ZrN-Si3N4 composite are 1 500 ℃ for 12 h.