The invention relates to trichoderma asperellum chlamydospore powder as well as a preparation method thereof and an application. The preparation method of the trichoderma asperellum chlamydospore powder comprises the following steps: conservatively culturing arsenic-resisting activity, purifying, culturing shake-flask seeds, culturing fermented seeds, controlling the fermentation and post-processing. The trichoderma asperellum chlamydospore is high in adversity resistance, the powder of the trichoderma asperellum chlamydospore is slightly subjected to the ambient temperature, acidicity, alkalinity and the like, and the influence of different arsenic concentrations in the environment on the sprouting of the chlamydospore is not obvious. The trichoderma asperellum chlamydospore has strong vitality, the survival time of the trichoderma asperellum chlamydospore is long, the volatilization of arsenic in the soil can be obviously promoted, the total quantity of the arsenic in the soil can be reduced, and the soil polluted by the arsenic can be effectively repaired. By adopting the method, the time for producing a great amount of trichoderma asperellum chlamydospore can be greatly shortened, the production cost of the trichoderma asperellum chlamydospore can be remarkably reduced, and the popularization of the technology can be favored.