The utility model discloses a dual power transfer switch's explosion chamber, including the arc -extinguish chamber that is " worker " type structure, " worker " type structure separates two independent arc extinguishing cavitys, and the lateral wall of arc -extinguish chamber has the mounting groove, is provided with multi -disc arc extinguishing bars piece in the arc extinguishing cavity, and the both sides of arc extinguishing bars piece are slipped into the mounting groove and are installed the back, by the spacing arc extinguishing bars piece of arc -extinguish chamber side installation fairings. The utility model discloses can make that arc extinguishing bars piece is more stable to be lain in it and to the bit position, then unifiedly come spacing arc extinguishing bars piece at arc-extinguish chamber side installation fairings, completion installation that can be quick is that the assembly of artifical still transfer machine is all very convenient, does not also need complicated manufacturing equipment and debugging, and improvement production efficiency that can be very big avoids original arc extinguishing bars piece to insert and establishes the both sides aperture andput tooling riveted troubles such as passing through the punch press in specific frock clamp again.