As a part of habitat networks,habitat migration corridors have great significance in ecological protection and biodiversity conservation. Studies on changing trends of corridors under multi-scale scenarios are critical in conservation planning implementation,especially for the case of fragmented landscapes. The Su-Xi-Chang region was selected as study area because of the fragile eco-environmental sensitivity due to rapid urbanization. The basic spatial cell unit is 30m. We constructed the habitat corridors of the Little Egret (Egretta garzetta) from size 2 to 20 by least-cost path method. The results indicate that landscape index is significantly affected by spatial grain: From size 2-11, the indexes fluctuate steadily, contain similar ecological process, which is deductible. However, under size 12-20, the index fluctuate prominently, grain size effect has great influence on corridor construction.