Abstract: The present invention discloses a two-body separated extraterrestrial body dielectric constant probe and its probing method. The device comprises: a surface body being on the surface of a penetrated medium after penetration—a surface body control module is set in the surface body, which comprises a first electromagnetic pulse emission source and a first electromagnetic pulse reception source; a penetrating body, connected to the surface body through a cable, being inside the penetrated medium after penetration—a penetrating body control module is set in the penetrating body, which comprises a second electromagnetic pulse emission source and a second electromagnetic pulse reception source. The present invention, relying on a kinetic energy penetration flight capability, can help to perform in-situ probing of dielectric constants at any position of an extraterrestrial body, for example, perform a penetration analysis through orbital-based release.