The utility model discloses a nut cracker. The nut cracker comprises a lower cover and an upper cover detachably connected with the lower cover. A tray is arranged at the bottom of the lower cover. A threaded hole opposite to the tray is formed in the upper cover. A threaded rod penetrates through the threaded hole to form threaded connection. A cylindrical extrusion part is arranged at the first end of the threaded rod, and a rotary knob is arranged at the second end of the threaded rod. One end of the extrusion part is closed and is fixed to the first end of the threaded rod through a fastener, a circle of sawteeth are arranged at the other end of the extrusion part along the cylinder wall, and the extrusion part gets close to or keeps away from the tray through rotation of the rotary knob to crack the shell of a nut. When the nut cracker is used, the rotary knob at the second end of the threaded rod is rotated to enable the extrusion part at the first end of the threaded rod to continuously get close to the tray, the sawteeth are used for fixing the nut, finally, the nut placed on the tray is extruded between the tray and the extrusion part, and the shell of the nut is forced to be cracked by the extrusion force formed by the tray and the extrusion part. The cracked nut is limited in the space defined by the upper cover and the lower cover, and therefore the flesh and the shell of the nut cannot be splashed.