Abstract: In this paper, the authors first describe the characteristics of x-ray determination of petrofabrics and selection of the samples, and proceed to discuss the relation of quartz fabric to the deformation of rocks and of the quartz grains themselves.After demonstrating how to transform quartz(1010) polar digrams to the sketch of quartz optic axis, an example is taken to illustrate that a combination of x-ray determination with other microstructural analysis or fabric study will yield more information for the research of geological structures.