The invention provides a digital signal processor, including a housing, a cover plate, a printed board assembly and a low frequency cable. The printed board assembly is composed of a signal processing circuit board, a power supply circuit board, an interface circuit board, an upper stud, a middle stud and a pillar stud. The signal processing circuit board, the power circuit board and the interface circuit board are arranged in a cascading way from top to bottom. The digital signal processor adopts the circuit board stacked installation way, occupies small space, reduces the equipment volume, and has a compact structure. The circuit boards are connected by using board connectors, so that the connection path is short, the loss is reduced, and the product performance, index and reliability are improved. Three layers of the circuit boards indirectly form a whole through the studs and the pillar, and after being debugged and qualified, the whole is installed in the housing for fastening. For repair or troubleshooting, simply removal of screws on the reverse side is only needed, and the entire printed board assembly can be taken out of the housing, thereby greatly improving the operability of the equipment and enabling installation and maintenance to be convenient.