The invention relates to a microbial oil displacement agent, the composition and weight of which are: coconut oil 50~80kg, starch 30~50kg, NaNO 3 6~8kg, K 2 HPO 4 2~2.5kg, KH 2 PO 4 1.5~2.5kg, NaCl 1~1.5kg, MgSO 4 0.3~0.5kg,K 2 SO 4 0.05-0.08 kg, Bacillus amyloliquefaciens bacteria liquid 10-40kg, lauryl alanine 80-100kg, deionized water 800-950kg. The invention also provides a preparation method of the microbial oil displacement agent. The microbial oil displacement agent of the present invention has strong oil washing ability, can effectively increase the oil recovery rate by 6-9%, has the characteristics of strong reliability, good use effect and high economic benefit as a whole, and is suitable for popularization and application in oil fields in a wide range.