The invention discloses a preparation method of a high-strength corrugated board and belongs to the technical field of papermaking; the high-strength corrugated board is made via the steps of secondary pretreating, grinding, beating, forming and the like. The yield, breaking length and ring crush index of crude pulp made by using the preparation method of crude pulp and high-strength corrugated boards are all significantly higher than those of the pulp made by using the prior art; the preparation method meets the national industrial policies of resource conservation, environmental friendliness, circular economy, and energy conservation and emission reduction, the redundant abandoned resources such as bagasse are developed and utilized, contamination can be decreased, and economic benefit can be increased.