The invention provides a compound cleaner as well as a preparation method and application thereof. The compound cleaner consists of the following raw materials in parts by volume: 15-30 parts of citric acid, 7-15 parts of sodium sulfate and10-20 parts of fatty alcohol-polyoxyethylene ether and is obtained by ultrasonically treating the raw materials for 10 minutes under action of 5kHz-ultraosnic waves and uniformly mixing the raw materials to obtain the compound cleaner. The compound cleaner can be used for removing PCB (Printed Circuit Board) golden finger discoloration pollution; the compound cleaner is simple and practical in composition, capable of effectively removing the PCB golden finger discoloration pollution; the preparation method of the compound cleaner is simple, is applied to removing the PCB golden finger discoloration pollution by preparing the compound cleaner in special volume content, and is simple and convenient to operate, so that not only is operation cost and production cost greatly lowered, but also PBC discoloration and a W/B (Water/Binder) de-soldering rate are lowered, and therefore, a first pass yield and quality of a product are improved, sample detecting efficiency is high, and needs of large-scale industrial production are adapted well.