The invention discloses a machining method of a fixed starting point thread. The machining method comprises the following steps: machining an outer-diameter size of a part to a thread to be machined state; then carrying out axial tool setting and circumferential tool setting respectively; finally, machining the fixed starting point thread according to a determined tool starting point. By adopting the machining method of the fixed starting point thread, the precision of a fixed starting point position can be effectively improved, and a difficulty barrier of machining the fixed starting point thread is broken; the reliable machining quality is guaranteed, and size consistency and interchangeability are good; the machining method of the fixed starting point thread has the effect of improving the machining efficiency and the yield.