Abstract
This paper explores the primary facfor for the decision of the Block size from the building depth size and the alley rate. The average size of the building depth is different at every use and the alley rate has the mutial relation with the Block depth size. But we can find the special Blocks having the high alley rate or the low alley rate. These facts mean that there are two kinds of Blocks, the small size Block and the large size Block for the Building and site size. Under the adaptation of these exploration, We propose two methods, the Reorganization by the exchanging the buidings of the different uses and the suitable Division of the Block depth.