A high voltage device with composite structure comprises a high voltage power MOS transistor HVNMOS and a JFET. The high voltage power MOS transistor HVNMOS comprises a drain, a source, a gate and a substrate, and a P-type well region Pwell as a conducting channel which is arranged between the source and the drain. The JFET comprises the drain, the source, the gate and the substrate, and an N-type well region Nwell as a conducting channel which is arranged between the source and the drain. The high voltage power MOS transistor HVNMOS and the JFET share the same drain, and the drain is processed by using N-type double diffusion process. The embodiment of the present invention further presents a starting circuit using the high voltage device with composite structure.