A tidal current energy generating device includes an outer frame (1), at least one inner frame (2), at least two hydro turbines (3), at least one center shaft (4), at least one generator (5), and at least three bearings (6). The at least one inner frame (2) is separably disposed in the outer frame (1). At least two hydro turbines (3) are located below a water surface and are disposed in one inner frame (2). At least two hydro turbines (3) are disposed coaxially and are vertical-axis hydro turbines. At least one center shaft (4) is disposed through the at least two hydro turbines (3), the axis direction of the center shaft is perpendicular to the horizontal plane, and the center shaft (4) rotates along with the rotating of the hydro turbines (3). The at least one generator (5) is located above the water surface and connected with one end of the center shaft (4). The at least three bearings are sleeved on the center shaft (4) and are located on two sides of and between the two hydro turbines (3), respectively. The tidal current energy generating device can be modularly assembled and replaced above the water surface and can extend along the water depth direction, thereby improving the power generating efficiency.