The invention relates to a precision machining method and a detection device for a flame stabilizer. The method comprises processes of argon arc welding, spraying of a high-temperature coating and thelike, shaping and correcting a part after each heat treatment process, and finally detecting an annular channel by using the detection device. The method fundamentally solves the influence of the process of spraying the high-temperature coating on the size of a precision lug hole, and a precision casting carries out machining to remove the allowance after the high-temperature coating and other high-temperature heating processes; the method improves the delivery qualification rate of the precision lug hole size of the part, can effectively detect the passing ability of the annular channel, removes interference points of the channel timely during the product machining process, ensures the technical requirements and assembly requirements of products, has stable product quality and good consistency, and meanwhile, the detection device has a simple structure, and can be popularized and used in various parts requiring processing of annular channel parts.