The invention relates to the technical field of biopesticides, and particularly relates to a granule virus dry suspending agent and a preparing method thereof. The dry suspending agent is mainly prepared by subjecting a granule virus aqueous suspending agent to pressurized spray drying and fluid-bed granulation, wherein a hot-wind inlet temperature of spray drying is 130-150 DEG C, an outlet temperature is 70-90 DEG C, and the temperature of a fluid bed is 50-70 DGE C. The granule virus aqueous suspending agent comprises a spray drying protective agent. Through setting temperature parameters of spray drying, and combining the spray drying protective agent added into the granule virus aqueous suspending agent, preparation of the dry suspending agent by adopting a spray drying wet-method granulation process is achieved, defects of dry-method granulation are overcome, the prepared dry suspending agent has high pest killing activity, good suspension, dispersing and disintegration properties, the suspending rate of the dry suspending agent is greater than 85%, dispersibility of the dry suspending agent is greater than 85%, the dry suspending agent has loose granules and is easy to disintegrate, and killing toxicity for corresponding pests can be 90% or above.