The invention relates to the technical field of pesticide combining, in particular to a pesticide composition, an application thereof and a preparation thereof. The pesticide composition comprises bacillus laterosporus and fludioxonil. The bacillus laterosporus and the fludioxonil are combined in a certain proportion, the synergistic effect can be generated, breeding of pathogenic bacteria (such as wheat sharp eyespot, corn stalk rot and cotton rhizoctonia) inside and outside plant materials can be suppressed, the growth of a plant root system can be promoted, the absorbing capacity of the root system can be improved, and therefore the crop yield can be increased.