The utility model discloses an assembled steel construction cooling tower of forming by six pole tetrahedron units, the cooling tower is connected the combination by a series of six pole tetrahedron modulus units according to certain law and is formed, the modulus unit comprises two chord members and four web members, two chord member space quadratures of modulus unit are arranged along the meridian orientation and the horizontal direction of cooling tower respectively, are called outer chord member and interior chord member, four extreme points of two chord members are connected to four web members, outer chord member has a perfect understanding along the meridian orientation in succession to be arranged, interior chord member forms closed ring at the horizontal direction, and outer chord member and interior chord member pass through the web member is connected, the cooling tower adopts the node of welded ball and ring flange combination. The utility model provides a cooling tower simple structure, construction convenient, be convenient for maintenance and low in cost.