Abstract: A review of studies on the mechanical properties and microscopic geometric models of three dimensional braided composites is given in this paper. The emphasis is placed on the recent developments of mechanical properties of three dimensional braided composites and author' s works in this field, in which the experimental and theoretical investigations into three dimensional braided composites are included. In theoretical investigations, elastic strain energy method, fiber inclination model, three cells model and finite element model etc. are introduced. Some future investigating trends are also presented.