Abstract: Appling least absolute deviation to calculate variable parameter of differential equation,robust grey model RGM(1,1)  has been set up and used to forecast the settlement tendency of building.The results show that，comparing with the normal GM(1，1) model，the robust GM(1,1) model has the advantages of better resistence against disturbance and less deviation by the influence of outlier.What’s more,RGM(1,1) which can be builded with little data,is more applicable useful than the other models.

Key words: grey model；robust grey model, least absolute deviation, settlement prediction