Abstract: The present invention provides an assembly platform of a large tidal current energy generating device. The assembly platform is internally provided with at least one horizontal axis hydro-generator. The assembly platform includes supports, at least four fixed piles, at least two sleeving members and at least two force-bearing supports. The fixed piles are connected through the supports to form an installation space. The hydro-generator is installed inside the installation space, one end of each fixed pile is driven to be fixed to a seabed and the other end extends to be above a water surface. Ends of the at least two force-bearing supports are respectively mounted on the left and right sides of the horizontal axis hydro-generator along the water flow direction and the other ends are respectively provided with corresponding sleeving members so as to resist an impact force of a water flow on the horizontal axis hydro-generator.