The invention discloses nylon composite material and a preparation method thereof. The material is composed of nylon 66 slices, thermotropic liquid crystalline polymer, needle-like mineral fiber, coupling agent and antioxidant. The weight ratio of the nylon 66 slices, the thermotropic liquid crystalline polymer, the needle-like mineral fiber, the coupling agent and the antioxidant is 60-70: 10-15: 20-30: 4.5: 0.5. The preparation method comprises the following steps: the nylon 66 slices, the thermotropic liquid crystalline polymer, the needle-like mineral fiber, the coupling agent and the antioxidant with weight ratio of 60-70: 10-15: 20-30: 4.5: 0.5 are mixed evenly under the agitating condition, and then extruded, drawn and granulated at 280 DEG C or 295 DEG C, and molded by injection into the sample to obtain the nylon system composite material. The nylon system of the invention can attain the remarkable enhancement effect under the circumstance of a little thermotropic liquid crystalline, and can have the effects on lightening the warping of the product, reducing the roughness of the product surface and reducing the cost.