The invention discloses a large synchronous motor stator cooling structure which comprises stator teeth. The stator teeth are provided with a stator slot and first water channels, the first water channels are arranged on two sides of the stator slot, an upper winding and a lower winding are arranged in the stator slot, a layer insulator is arranged between the upper winding and the lower winding,main insulators are arranged on the peripheries of the upper winding and the lower winding, second water channels are arranged on the main insulators, a slot wedge is arranged in the stator slot, a filler strip is arranged between the slot wedge and the lower winding, the upper winding and the lower winding comprise a plurality of rows of braided wires, row insulators are arranged among the braided wires, the braided wires comprise alternate solid conductor groups and hollow conductors, turn-to-turn insulators are arranged among the solid conductor groups and the hollow conductors and among solid conductors inside the solid conductor groups, third water channels are arranged inside the hollow conductors, and cooling media are led into the first water channels, the second water channels andthe third water channels. The cooling effect of the upper winding, the lower winding and the stator teeth is improved, and the safe and stable operation capacity of a motor is improved.