Abstract: Since threedimension multidirectional braided composites have many advantages which can not be substituted, it is called reinforcedfiber composites of the third generation. In this paper, the unit cell model is established and verified for fourdirectional braided composites. The experimental data agree very well with the results predicted by the theoretical analysis. The effectiveness of the present model becomes the basis of properties analysis and optimum design of threedimensional braided composites.