The invention provides an inorganic composite gasket and a preparation method thereof. The inorganic composite gasket comprises a compound which consists of an inorganic non-metallic fiber, an expansile material and bond, wherein, the inorganic composite gasket is divided into eight width sections in the width direction and is divided into three thickness layers from inside to outside; componentsof gaskets materials in each thickness layer and width section are the same or different, wherein, the expansile material in the three thickness layers have different contents, wherein, the inner layer occupies 33.3 to 50 percent of the total content, the intermediate layer occupies 30 to 40 percent of the total content, and the outer layer occupies 20 to 33.3 percent of the total content. The inorganic composite gasket has the advantages of breaking through the prior uniform gasket according to the requirement of the gasket in practical application to enable the components of the gasket to form asymmetrical distribution in the thickness direction and the width direction and meet the practical application requirement, and adopting a novel vacuum suction filtering technology to prepare theinorganic composite gasket with the method of composite molding, so that a product can achieve the excellent functions of fixing, sealing, heat insulating and sound-absorbing. The inorganic compositegasket can be applied to a catalytic converter of a motor vehicle.