The invention discloses an automatic compressor for household garbage. An ordinary garbage compressor cannot adapt to effective treatment of household garbage or garbage on small sites. The center of a compression pushing plate and a transmission lead screw form a screw pair; the compression pushing plate and a compression piston are fixedly connected through four compression supporting columns; the compression piston and a compression cavity form a sliding pair; a first transmission gear is fixedly connected to the transmission lead screw and engaged with a second transmission gear; the second transmission gear is fixedly connected to a first transmission shaft and engaged with the first transmission gear and a third transmission gear; the third transmission gear and a fourth transmission gear are fixedly connected to a second transmission shaft; the fourth transmission gear and a fifth transmission gear are engaged; the fifth transmission gear is fixedly connected to a third transmission shaft and engaged with the fourth transmission gear and a sixth transmission gear; the sixth transmission gear is fixedly connected to a fourth transmission shaft; a motor drives the fourth transmission shaft. The automatic compressor for household garbage can automatically and rapidly compress garbage, and compression force is large due to a power enhanced mechanism of the multiple stages of gears.