The invention discloses a metal liquid deep-layer sampling device. The metal liquid deep-layer sampling device comprises a sampling device body, wherein the sampling device body is of a cavity pipe structure; a sampling metal liquid inlet is formed in one end of the sampling device body, a plugging cap is mounted at the inlet and the other end of the sampling metal liquid inlet is sealed through a thread end cap; the plugging cap is made of material same as that of sampling metal liquid; the middle part of the sampling device body is connected with a steel pipe through a connecting pipe and the connecting pipe and the steel pipe are hollow pipes; an opening end of the connecting pipe stretches into the sampling device body; the opening end of the connecting pipe is internally filled with a ventilation plug and aluminum silicate wool; when the metal liquid is deeply sampled, the metal liquid is used for melting the plugging cap; the metal liquid enters the sampling device body through the inlet; meanwhile, air in the sampling device body is discharged through the ventilation plug and the aluminum silicate wool in the connecting pipe. The metal liquid deep-layer sampling device can be used for sampling at any depth position of aluminum liquid and data including components of each depth, density equivalent, hydrogen content, modification effect and the like of alloy liquid can be really reflected, and reliable technical data is provided for reduction of unqualified products.