The invention discloses a parallel bus device for an LED display screen unit board which comprises a highest bit address bus, a lowest bit address bus, a synchronous controller, an address counter and an internal address bus. The lowest bit address bus and the highest bit address bus are respectively connected with two input terminals of the synchronous controller; an output terminal of the synchronous controller and an output terminal of the lowest address bus are respectively connected with two input terminals of the address counter; the address counter is connected with a subsequent decoding output circuit through the internal address bus. According to the parallel bus device, a traditional parallel bus is replaced with two address buses, large phase difference caused by an excessive number of address line buses and tandem connection unit boards can be reduced, accuracy of the output signals can be ensured, control effect can be improved, and cost can be lowered.