This invention provides a rolling bearing protection device and a vertical-axis tidal current energy generating device applying the same. The vertical-axis tidal current energy generating device includes a frame, a vertical-axis hydraulic generator, a rolling bearing, and a rolling bearing protection device. The vertical-axis hydraulic generator includes a main shaft disposed vertical to a horizontal surface, one end of the main shaft is rotatably disposed at a bottom of the frame. The rolling bearing is sleeved on one end of the main shaft. The rolling bearing protection device is disposed above the rolling bearing. The rolling bearing protection device includes a first sealing protection device, a first water leak-proof chamber, and a second sealing protection device disposed in sequence along a gravity direction.