A LED lamp string of easy welding, assembly and injection includes at least one rectifier, and multiple LED modules connected in series between positive and negative output ends of the at least one rectifier. Each LED module includes a first PCB, and the first PCB is provided with multiple first welding positions. The first welding positions are welded with a lamp bead and wires thereon. The lamp bead is connected to first ends of the wires, and a second end of the one wire of each LED module is directly connected to the at least one rectifier or is connected to the at least one rectifier after passing through at least one other LED module. It can realize the large-scale production of the welding equipment instead of manual welding, greatly improve the efficiency of the production, avoid false welding and improve the yield rate.