The invention discloses a rock core wire cutting and sample splitting device which comprises a machine body, a workbench is arranged on the machine body, a first supporting arm and a second supporting arm which are connected to the machine body are arranged above the workbench, a diamond wire is arranged between the first supporting arm and the second supporting arm, a first supporting plate is arranged on the workbench, and a first supporting column is arranged at the upper end of the first supporting plate; a first rotating motor is arranged on the side, away from the diamond wire, of the first supporting column, a rotating disc is arranged on the side, close to the diamond wire, of the first supporting column, an output shaft of the first rotating motor is connected to the rotating disc, a supporting disc is installed on the side, close to the diamond wire, of the rotating disc, and four supporting rods are evenly arranged on the edge of the side, close to the diamond wire, of the supporting disc. Pressing strips are arranged on the sides, close to the axis, of the four supporting rods, first automatic telescopic rods are arranged in the supporting rods, and one ends of the first automatic telescopic rods stretch out of the supporting rods to be connected to the pressing strips. The fixed rock core is cut through the diamond wire, cutting is uniform, cutting seams are small, and waste of the rock core is reduced.