A dual colored LED decoration lamp which includes a lamp string combined of multiple dual colored LED lights and a controller connected between the power supply and the lamp string. The lamp string includes lamp groups combined of multiple LED lights with two different colors and with their anodes and cathodes cross-linked. The multiple lamp groups are then connected in series, and each LED light in every lamp group is connected in same direction with the same colored LED light in the next lamp group. The controller controls the variation of the direction of current in aforementioned lamp strings. Thus, the lamp string is able to emit light with different colors by varying the current direction in the same lamp string through the usage of controller, and there is no need to set with multiple lamp strings.