Disclosed is an improved lamp circuit of a liquid crystal device (LCD) backlight source, comprising a printed circuit board (PCB) for lamp initialization having a control circuit and a first connector thereon; a first lamp connection board disposed between the first lamp connection board and a second lamp connection board and being lamps of the LCD backlight source; a second lamp connection board having a second connector and transformers thereon, the transformers each corresponding to one of the lamps; and a low voltage wire set connected between the first connector on the PCB for lamp initialization and the second connector on the second lamp connection board, wherein a signal issued from the first connector on the PCB for lamp initialization is transmitted through the low voltage wire set to the second connector on the first PCB for lamp initialization and then to a corresponding one of the transformers so that the lamps may be driven to operate. With use of the present invention, number of the used connectors may be reduced and arrangement issue of the high voltage wires may be obviated, making volume of the PCB for lamp initialization allowed to be reduced and cost of the lamp circuit lowered.