The invention discloses a high-reliability bipolar device for a transverse insulated gate, and a preparation method of the high-reliability bipolar device. The high-reliability bipolar device comprises a P-shaped substrate, a buried oxide layer, an N-shaped drift region and a silicon-dioxide layer, wherein the P-shaped body regions and an N-shaped buffer layer are arranged in an N-shaped epitaxial layer, P-shaped emitting electrodes and N-shaped emitting electrodes are arranged in the P-shaped body regions, and a metal electrode connection wire of the emitting electrodes is connected to the P-shaped emitting electrodes and the N-shaped emitting electrodes; a P-shaped collector electrode is arranged in the N-shaped buffer layer, and collector electrode metal is connected to the P-shaped collector electrode; polysilicon gates and polysilicon field plates are arranged in the silicon-dioxide layer, and gate metal is connected to the polysilicon gates; a row of grooves is also formed in the N-shaped drift region, a layer of silicon dioxide is arranged on the inner wall of each groove, the silicon dioxide is filled with polysilicon, the grooves are adjacent to the P-shaped body regions, the P-shaped emitting electrodes, the N-shaped emitting electrodes, and the U-shaped openings of the polysilicon gates, and the grooves are positioned below the connector electrode metal and are perpendicular to the connector electrode metal.