The invention provides an interlayer insulation layer and a preparation method therefor, and a liquid crystal display panel. The preparation method comprises the following steps of S1, performing deposition of a first SiN layer with low refractive index and a second SiN layer with high refractive index on a substrate in sequence, wherein low refractive index is 1.7-1.87, high refractive index is 1.91-1.93, and x is greater than or equal to 1; and S2, depositing an SiO layer on the second SiN layer, wherein the refractive index of the SiO layer is 1.4-1.5, and y is greater than or equal to 1. The interlayer insulation layer provided by the invention is high in elasticity and stability, relatively low in stress, and capable of lowering influence on long-distance precision of low-temperature polysilicon, without damaging a film layer nor causing film layer crack and stripping.