Silicone resin is the mainly adhesive in mica insulation industry, and this sort of adhesive is easy to produce toxic and harmful volatile organic compounds and causing the environment pollution. Under the premise of no decrease in insulation performance of the mica composite insulation material, the environmental friendly modified starch adhesive is chosen. In order to obtain the high performance composite materials, the improvement of its flexural strength is necessary, and the method of modification is introduced. Four kinds of modified starch, such as: maize soluble starch, oxidized starch, β-dextrin and cationic starch are discussed. The cationic starch is avaliable as the bond medium and the silicone coupling agent KH-550 is used for modified enhancement. When the dosage of the cationic starch is 10% and modified 30mins by silicone coupling agent KH-550 with the concentration of 1%, the flexural strength and dielectric strength of the mica composite insulation material can reach 248.5 N/mm2 and 23.16 KV/mm respectively.