To use a stochastic optimization algorithm to search an optimum placement, the representation of the configuration of a placement is the most important and fundamental issue. A new Constraint Graph based representation SL was devised in the paper to represent the non slicing structure of placement. A nearly O(n) placement algorithm can be designed over the SL representation. With the assumption of the meta grid, we can derive a new concise representation for non slicing structures from SL representation.With assumption of the meta-grid,we can derive a new concise representation for non-slicing structures from SL.We name the new representation as Stairway Grid(SG)model.It needs n(2「lg n」)bits fora placement of nrectangular blocks.The solution space of SGrepresentation,it takes onlyO(n)time to transform it to its corresponding placement.It had been proved that all slicing structures could be represented by SG.And SGmodel also can represent non-slicing structure.Experimental results on SG model demonstrated that it is a concise and effective representation of non-slicing structure.