This talk is based on my Thesis. By constructing (non-canonical) deformations for the associated p-divisible groups of the special fibre S of a Shimura variety, we manage to construct a morphism from S to some quotient sheaf of the loop group associated with S. We show that the geometric fibre of this morphism gives back the Ekedahl-Oort strata of S: this also gives a conceptual interpretation of Viehmann's new invariant "elements of truncation of level one".  I will recall the Ekedahl-Oort stratification of Shimura varieties (of good reduction) and the classification of p-divisible groups in terms of filtered Breuil-Kisin modules (or Breuil-Kisin windows, in my term), and then present the strategy of constructing the morphism aforementioned.