Abstract: Based on the model of GM（1,1） of grey system,the residual model and the equal dimensional new information model were used to modify it and the im itation of P-s curve and forcast of ultimate bearing capacity of the single pi le were implemented in this paper.And the grey model theory had a practical mea ning for the forecast of single pile.Less information,brief calculation and hi gh precision are the advantanges of grey forecast.With the help of computer,we can get the quick analysis,reliable forecast.So the grey forecast has a pract ical value in engineering.