Transformer

The invention discloses a transformer, and the transformer can completely guarantee the creep distance between a primary winding and a secondary winding. The transformer is provided with a spool (10), wherein the periphery of a cylindrical part (11) is provided with a flange (13); the primary winding (21) and the secondary winding (22) which clamp the flange (13), are adjacent to the flange (13), and are wound; an iron core which is assembled in the cylindrical part (11); a housing (40), wherein an inner side of the housing (40) is provided with first bulge strip parts (41, 42), and the housing (40) covers the spool (10); and a bottom plate (50), wherein the upper surface of the bottom plate (50) is provided with a second bulge strip part (51) and the bottom plate (50) is disposed at the lower side of the spool (10). The outer edge of the flange (13) is provided with annular concave part (17). The first bulge strip parts (41, 42) and the second bulge strip part (51) are distributed at the periphery and are embedded into the concave part (17). During observation from a reel direction of the spool (10), two ends of each of the first bulge strip parts (41, 42) and two ends of the second bulge strip part (51) are overlapped. In addition, the span of the overlapped parts is from an inner side of the concave part (17) and an outer side of the flange (13).