Provided is a method for preparing furfural. The method comprises: mixing a plant raw material and an acid containing a —SO3H functional group for pre-treating, then mixing same with an organic acid, cooking same, and then subjecting same to solid-liquid separation, so as to obtain a hemicellulose sugar solution; introducing the resulting hemicellulose sugar solution from the upper part of a reaction kettle, and at the same time, introducing an acetic acid steam from the lower part of the reaction kettle, such that the sugar solution and the acetic acid steam come into contact in a counter-current manner and react so as to form a furfural steam; after the reaction is completed, discharging the furfural steam from the upper part of the reaction kettle; and cooling same so as to obtain a solution containing furfural. In the method, by means of firstly pre-treating the plant raw material using the acid containing a —SO3H functional group, and then cooking same with the organic acid, the hydrolysis rate of pentosan in a hemicellulose can reach 99% or more, thus achieving efficient use of valuable substances in the raw material. In addition, the method relates to a process for discharging the furfural steam in batches and semi-continuously, has an improved furfural production rate, which rate can reach 65-75%, and has good economic benefits and application prospects.