A method for killing fly type pests in a trapping device through diatomaceous earth in a non-toxic mode includes the steps of firstly, forming the waterproof fly trapping device through waterproof materials; secondly, throwing the diatomaceous earth in a pest collection device or a collection area of the trapping device or spraying the diatomaceous earth to the outer surface of the fly trapping device. Once flies enter and set foot on the pest collection device or the collection area in the trapping device, fine particles of the diatomaceous earth can be instantly attached to body surfaces of the flies, the flies can instantly feel uncomfortable and can not struggle at the moment, and therefore the flies can not escape and can die from body dehydration within a short period of time, an extremely small number of flies can escape but can automatically die within a short period of time as well after escaping, and death of the escaped flies can not be influenced by any external environment. The method has the advantages of being advanced in science and technology, environmentally friendly, free of toxin, capable of saving energy, reducing cost and reducing pollution, high in killing rate, beneficial to scientific research, remarkable in effect, capable of purifying the environment, and the like, and the method has extra economic and social benefits.