Abstract: Strained semiconductor microstructures are one of the most attractive and important materials for both basic study and device applications. Lattice mismatch and misorientation are common in the strained semiconductors, while there are still some problems with measurement of misorentation in the epilayers by conventional method of x-ray diffraction. In this paper, a method of x-ray diffraction with simple geometry was developed to quantitatively analyze the structure of strained epilayer with a tilting angle to the substrate. An X′Pert four crystal x-ray diffractometer with high accuracy (1/10000 degree) and high resolution was used to demonstrate the proposed method on a InGaAs. InAlAs/InP microstructure grown by gas source molecular beam epitaxy. Results showed an excellent consistency between data measured and calculated from the model. It was pointed out that the conventional 180⁰-rotation twice measurement method usually got a value smaller than the real value of the tilting angle.