A flexible circuit board of a hearing aid and the hearing aid are provided. The flexible circuit board has an annular portion bent into an annular shape, wherein the annular portion is used for surrounding a peripheral side of a battery, and an outer side surface of the annular portion has pads; the flexible circuit board has a device portion located on a front side of the annular portion, wherein the device portion is used for installing electronic devices and is used for electrically connecting a receiver; the flexible circuit board has a chip portion connected to a bottom end of the annular portion, wherein the chip portion is used for binding a chip. The flexible circuit board strings together the receiver, the chip and the battery into a compact structure.