The invention provides a material for improving quality of a drilling fluid filter cake, and a preparation and application method thereof. The material is prepared from nano silicon dioxide and meerschaum. The preparation method comprises the following steps: mixing the nano silicon dioxide and meerschaum, and dispersing by using an energy-gathered ultrasonic material emulsifying dispersion instrument; calcining at 300-500 DEG C for 2-5 hours; and finally, dispersing by using the energy-gathered ultrasonic material emulsifying dispersion instrument. The application method is implemented by adding 1-3 wt% of the material into a drilling fluid. According to the invention, under the condition that the nano particles can enter the micropores and microcracks of the filter cake, the compactness of the filter cake is enhanced; the fiber structure of the meerschaum can be utilized to form bridges for the pores and cracks of the filter cake, so that the plugging layer can be formed and the permeability of the filter cake can be reduced. The fiber structure of the meerschaum can enhance the toughness of the filter cake, thereby further enhancing the lubricating property of the filter cake.