The invention discloses a method for separating and recycling acetaldehyde. The method comprises steps of preheating, gas stripping, absorption and the like, and concretely comprises the following steps: a material liquid to be processed which is preheated is sprayed from a top part of a gas stripping tower, carried acetaldehyde is blown out through gas bubbling or counter current, a dilute solution is obtained through carrying out multistage absorbing on a gas containing acetaldehyde by an absorbing tower spraying solvent, and concentrated acetaldehyde is obtained through vacuum concentration. The method allows the yield of acetaldehyde to be high and a problem of product discoloration in direct distillation in prior art to be avoided, and simultaneously allows environmental pollution caused by decolorizing with active carbon to be avoided, energy and auxiliary materials to be saved and production cost to be reduced. The method is suitable for a system of separating and recycling acetaldehyde in a reaction liquid when glyoxal is prepared through oxidizing acetaldehyde which is treated as an initial raw material by nitric acid, and can be widely applied to recycle and separate low-boiling materials in other thermal sensitive materials.