The invention discloses a ground assembling device for an impeller of a wind driven generator. The ground assembling device comprises a wheel-hub jacking platform, balance supporting legs, blade supporting frames and counter weight plates. The wheel-hub jacking platform comprises a jacking disc, an upper supporting disc, a middle supporting disc and a lower supporting disc, wherein the jacking disc is a round steel disc, and the upper supporting disc, the middle supporting disc and the lower supporting disc are of a circular ring-shaped steel disc structure. Each balance supporting leg comprises a main supporting leg, and the portion, close to the first end, of the main supporting leg is sleeved with a casing pipe in a sliding mode. Each blade supporting frame comprises a supporting disc, a protective pad and a supporting system, wherein the protective pad is installed on the upper surface of the supporting disc, and the supporting system connected with the lower surface of the supporting disc is arranged below the supporting disc. When the ground assembling device for the impeller of the wind driven generator is used, the operating space can be decreased; secondly, by adopting the device, the height of the impeller can be flexibly adjusted according to topographical changes of a construction area, and the variable pitch operation of the impeller of the wind driven generator can be achieved conveniently; finally, the device is good in balance performance, the situation that the device overturnes due to unstable gravity center can be effectively avoided, the working efficiency is improved, and the construction cost is reduced.