NOVELTY - A Paecilomyces cicadae biological microbial agent comprises P. cicadae, culture medium, auxiliary material and carrier. The culture medium comprises (pts. wt.): protein powder (100-300), silkworm chrysalis powder (100-300), willow bark powder (10-40), tea leaf powder (5-10) and water (1000-1500). The auxiliary material is mixture of protein powder and silkworm chrysalis powder. The carrier is mixture of poplar bark powder, willow bark powder, pear bark powder, elm bark powder, thorn acacia bark powder, persimmon bark powder and orange bark powder.    USE - Paecilomyces cicadae biological microbial agent used in pesticide for preventing and controlling plant nematodes, killing inquilinous and half-inquilinous plant nematodes or killing grub and leek grub.    ADVANTAGE - The microbial agent is stable in performance and wide in application range; is accordant with standard of shelf life of biological agrochemical; is environment-friendly, and safe and healthy to human being; meets the needs of production of organic food and environment-friendly food; and is suitable for industrial batch production.    DETAILED DESCRIPTION - The Paecilomyces cicadae biological microbial agent comprises P. cicadae, culture medium, auxiliary material and carrier. The culture medium comprises (pts. wt.): protein powder (100-300), silkworm chrysalis powder (100-300), willow bark powder (10-40), tea leaf powder (5-10) and water (1000-1500). The auxiliary material is mixture of protein powder and silkworm chrysalis powder. The carrier is mixture of poplar bark powder, willow bark powder, pear bark powder, elm bark powder, thorn acacia bark powder, persimmon bark powder and orange bark powder. The protein powder is egg powder and/or peptone powder. An INDEPENDENT CLAIM is included for a method for preparing P. cicadae biological microbial agent comprising preparing seed, fermenting with first stage of seeding tank, fermenting with second stage of seeding tank, and producing microbial agent. The preparation of seed involves extracting P. cicadae with water or alcohol deposition to obtain P. cicadae strain; culturing seed on culture medium with liquid shaking way or by slant test tube under liquid state, where 0.01-5 g of strain is employed for every gram of culture medium; mixing ingredient of culture medium with strain, and placing mixture at environment of 0-30 degrees C; and culturing mixture for 6-12 days in a ventilated environment to obtain P. cicadae seed. The fermentation with first stage of seeding tank involves mixing P. cicadae seed with water at wt. ratio of 1:1000-1500, and adding 40-70% first stage of culture medium into mixture; and breeding mixture for 6-12 days at - 15-45 degrees C to obtain first stage of seed. The fermentation of second stage of seeding tank involves mixing first stage of seed with water at wt. ratio of 1:3-40, and adding 40-70% of second stage of culture medium into mixture; and breeding mixture for 6-12 days at - 15-45 degrees C to obtain second stage of seed. The production of microbial agent involves producing preparation from second stage of seed from 3 different methods. The first method includes adding (pts. wt.) water (12000-16000), second stage of seed (100-200), protein powder or silkworm chrysalis powder (1500-3500), willow bark powder (200-1200) and tea leaf powder (40-100) in a fermentation cylinder; and culturing mixture for 6-12 days in a ventilated environment at 10-45 degrees C, and packing obtained material to obtain liquid agent. The second method includes absorbing second stage of seed with auxiliary material and carrier; drying absorbed seed at 10-50 degrees C or freeze-drying seed to obtain powder or granule that is powder agent. The third method includes adding 5-20% of second stage of seed into water to obtain mixture of second stage of seed; mixing obtained mixture of second stage of seed with preparation culture medium at wt. ratio of 1:0.8-1.2; breeding mixture for 8-20 days at 10-45 degrees C; and drying mixture at 10-50 degrees C or freeze-drying mixture to obtain solid material that is solid agent.