The invention discloses an ocean tidal current energy power generating system. The ocean tidal current energy power generating system comprises a fixing mechanism, an ocean current energy power generator set and a signal monitoring mechanism; the fixing mechanism comprises a floating body, fixing rods, a horizontal supporting rod and a working platform, the floating body is fixed to the seabed through anchor chains, the fixing rods are fixed to the floating body, the horizontal supporting rod is fixed to the underwater portions of the fixing rods, and the working platform is fixed to the overwater portions of the fixing rods; the ocean current energy power generator set comprises underwater assemblies and an overwater assembly; each underwater assembly comprises blades, a wheel hub, a power generator and a yawing mechanism which are connected in sequence, a variable propeller mechanism is arranged in the wheel hub, and the yawing mechanism is arranged between the power generator and the horizontal supporting rod; the overwater assembly comprises a converter and a control cabinet; and the signal monitoring mechanism comprises an ocean current meter connected with the control cabinet, and the ocean current meter is arranged on the horizontal supporting rod. The ocean tidal current energy power generating system adopts a floating type ocean tidal current energy power generating system, is a direct driving type wind generator set, and can safely and reliably convert ocean current energy into electric energy efficiently.