Nanocomposite materials use matrix resin and rubber as continuous phases, and modifier semiconductor nanometers and nanometals as dispersed phases. The modifier is evenly dispersed into the body material according to a certain preparation method. Compound mechanism. This article aims to study the effect of silane coupling agent on the structure and properties of polymethyl methacrylate silica nanocomposites. This article mainly uses nano-silica as the basic material and uses organic functional molecules for modification to prepare three new materials that can selectively adsorb gold ions, which provides new ideas for the concentration and recovery of gold ions. This paper mainly uses the isotherm adsorption algorithm to calculate the relationship between the concentration of different adsorbate and adsorption capacity at a specific temperature for nanocomposites. The experimental results in this paper show that polymethyl methacrylate silica nanocomposites can selectively adsorb gold ions, the maximum adsorption capacity is 127.3 mg/g, the adsorption equilibrium time is 20 min, and the optimal adsorption pH is 3.