Provided is a flexible temperature sensor including a flexible temperature-sensing fabric, wherein the flexible temperature-sensing fabric includes a fabric base and at least one flexible temperature-sensing conductive fiber, the fabric base is a flat fabric woven from a plurality of insulating fibers, and the temperature-sensing conductive fiber is fixed in the fabric base by weaving. The flexible temperature sensor has the advantages of being easy to fabricate, low in cost, washable, wide in temperature monitoring range, high in sensitivity, good in stability and repeatability, and compatible with existing textile technologies.