A sound generator comprises a shell, a vibration system and a magnetic circuit system sequentially accommodated and fixed at a first end of the shell from top to bottom; the magnetic circuit system is provided with a rear sound hole; the shell comprises a first portion corresponding to the vibration system and the magnetic circuit system, and a second portion integrally extending downward from the first portion beyond a bottom surface of the magnetic circuit system. A second end portion of the shell is integrally provided with a shell bottom wall or separately mounted with a lower cover plate; and a rear cavity in communication with the rear sound hole is formed.