The invention discloses an ectropic obliqua nuclear polyhedrosis virus bacillus thuringiensis desinsection suspending agent and a preparation method thereof. The agent mainly comprises the ectropic obliqua nuclear polyhedrosis virus and the bacillus thuringiensis, wherein the content of the inclusion body of the ectropic obliqua nuclear polyhedrosis virus is (1.0x10<6>-1.0x10<10>)PIB/mL, and the content of the bacillus thuringiensis is between 3.0 and 25.0 percent. The ectropic obliqua nuclear polyhedrosis virus bacillus thuringiensis desinsection suspending agent comprises the ectropic obliqua nuclear polyhedrosis virus, the bacillus thuringiensis, polycarboxylate, sodium lignosulfonate, dioctyl sulfo succinic acid, alkyl sulfonate, white carbon black, magnesium aluminum silicatenf, sodium benzoate, xanthan gum, carboxymethyl cellulose, polyvinyl alcohol, glycol, propanediol, organosilicon defoamer and water which are mixed according to certain ratio. The agent and the preparation method thereof are not harmful to environment, organisms and human bodies, do not pollute the environment or have residue, and can effectively control the generation and harm of the ectropic obliqua; and the agent is suitable for the application in a large quantity, has long persistent period, increases the speed of the virus to kill pests, and ensures that the desinsection time of the virus pesticide is shortened to three to five days.