The invention relates to the technical field of pesticide, and in particular relates to entomogenous nematode powder and a preparation method thereof. The entomogenous nematode powder consists of the following components in percentage by weight: 20-40% of a500-5000 thousand pieces/g entomogenous nematode suspension, 0.2-1.0% of a water retention agent, 0.2-1.0% of a stabilizer, 0.1-0.5% of an anti-molding agent, 40-50% of a carrier and 10-30% of water. The preparation method comprises the following steps: uniformly mixing the components, and screening, thereby obtaining the entomogenous nematode powder. The entomogenous nematode powder provided by the invention is convenient to use, long in low-temperature storage period, convenient to transport and high in survival rate. The preparation method provided by the invention is simple, convenient and rapid to operate and applicable to industrial production.