Abstract: 3D models of(interior,surface and corner) unit cells of the 3D braiding preform were established based on the characteristics of 3D entity modeling of Pro/E.Parameterized models were designed.Every kind of unit cell model can be auto created under different braiding parameters,and according to Pro/E model— analyzed function,the fabric volume of a cell can be output directly.The calculation formula of the perform fabric volume fraction was proposed based on parameterized cell models.The fabric volume fraction of the rectangular perform was calculated,and it is well in agreement with experiment result.The fabric volume fraction of annular sector perform was also calculated.It provides a new method for calculating fabric volume fraction of complex shape.