Abstract: The present disclosure provides a device and methods for determining the original stratum direction of a core. The device includes a confining pressure pump, a resistance meter, and a core holder composed of upper and lower portions. The present disclosure further provides three methods for determining the original stratum direction of the core. The three methods respectively use the device to measure resistance values at different positions of the core, and compare a test result with an imaging result of resistivity imaging logging data to determine the rock direction of the core in a stratum.