The invention discloses a method for plating surfaces of diamonds with silicon oxide coating materials through thermal treatment. Silicon powder and silicon blocks can be used as a silicon source, wherein purity is 99.0wt%. The granularity of plated diamond particles is 20-200 micrometers. The silicon source is evaporated through thermal treatment so that surfaces of diamonds can be plated with silicon oxide. Diamonds plated with silicon oxide are mainly prepared through the following steps that firstly, silicon powder and diamonds are placed in a crucible, and a square aluminium oxide cushion block is placed below diamond particles; and secondly, the crucible is covered with an aluminum oxide gasket, and the crucible is placed in a tubular furnace for thermal treatment. The heating rate of thermal treatment is 5-10 DEG C/min, the temperature is 1300-1500 DEG C, the heat preservation time is 0.5-1 h, the heating rate is 7 DEG C/min, and the vacuum degree is about 1-10 Pa. Surfaces of obtained diamond particle products are plated with silicon oxide coatings. The adopted thermal treatment process is simple, high in repeatability and high in yield.