The invention provides a peanut plant growth regulator and a preparation and use method thereof. The peanut plant growth regulator includes three specific components with specific amount proportion, has excellent effect on controlling peanut flourishing growth, has short effect-lasting period, cannot affect the growth of after-reap crops, has low cost, and can effectively improve the yield of peanuts and improve the economy benefits. The preparation and use method of the peanut plant growth regulator is simple in process, corresponding components are applied in different planting periods of peanuts, the peanut flourishing growth can be effectively controlled, the cost is low, the peanut yield is effectively improved and the economic benefit is improved.