The invention provides a system and a method for processing signals of virtual surrounds of four loudspeakers. The system comprises an input module, a first sound mixer, a second sound mixer, a third sound mixer, a fourth sound mixer, a digital and analog converter, a left front loudspeaker, a right front loudspeaker, a left rear loudspeaker and a right rear loudspeaker, wherein the first sound mixer is used for mixing signals of a left sound channel, a center channel and a mega bass sound channel so as to acquire a first sound channel signal; the second sound mixer is used for mixing signals of a right sound channel, the center sound channel and the mega bass sound channel so as to acquire a second sound channel signal, the third sound mixer is used for mixing signals of a left rear surround sound channel and the mega bass sound channel so as to acquire a third sound channel signal; the fourth sound mixer is used for mixing signals of a right rear surround sound channel and the mega bass sound channel so as to acquire a fourth sound channel signal; the digital and analog converter is used for respectively converting the first sound channel signal, the second sound channel signal, the third sound channel signal and the fourth sound channel signal into a first audio, a second audio, a third audio and a fourth audio; and the four loudspeakers are respectively used for playing the first audio to the fourth audio. By the system, cost is saved, surround sound effect is good and signal processing is simple and easy to realize.