The invention discloses a controlled silicon device under auxiliary trigger of an embedded P-type MOS (Metal Oxide Semiconductor) transistor. A second N well without being connected with any potential is additionally arranged on a P-type substrate between a second P+ injection region and a second N+ injection region, thus a longitudinal base width of a parasitic NPN (Negative Positive Negative) triode can be effectively increased. By using the special characteristic of low-voltage starting of the embedded P-type MOS transistor, the controlled silicon device realizes low-voltage starting of controlled silicon, and is suitable for ESD (Electronic Static Discharge) protection requirements of most of circuits. Meanwhile, by using a manner of increasing a potential floating N well, the controlled silicon device achieves the purpose of increasing a clamp voltage of the controlled silicon. In addition, compared with the traditional method of purely depending on drawing the transverse base width of the triode, the controlled silicon device provided by the invention has higher efficiency on the area, is more beneficial to saving of a silicon wafer area and production cost, and is an economic and effective low-working-voltage-domain circuit ESD protective scheme. The controlled silicon device disclosed by the invention has the advantages of simple structure, uniform current, strong device property, stability and reliability.