The invention discloses an acid soil restoration agent as well as a preparation method and application thereof. The acid soil restoration agent is prepared from the following raw materials in parts by weight: 30 to 80 parts of biomass ash, 5 to 30 parts of phosphate ore powder, 3 to 30 parts of tobacco stem powder and 3 to 30 parts of egg shell powder. The acid soil restoration agent can increase the pH value of acid soil, supply abundant medium trace elements for soil and inhibit the pests and diseases. The problem of environmental pollution such as stacking, difficulty in storage, flying dust and high pH value of biomass ash produced by biomass power plants is solved, and comprehensive utilization of waste resources such as biomass ash, tobacco stems and egg shell is realized.