This paper treats the spatial distribution of multiple matrix cracking in fiber-reinforced ceramics matrix composites. In-situ observation was carried out on a carbon fiber-reinforced PYREX glass composite on tensile loading, and the spatial distribution of the matrix cracks was determined by a compare check on its optical micrographs. A stochastic model is developed with an assumption that a new matrix crack is generated only in the effective cell in which the matrix stress remains uniformly high. As compared with the experimental data, the average position of the matrix cracks in the effective cell coincides well with the prediction by the theory; however, the standard deviation is still slightly different from it. The discrepancy is discussed in relation to the underestimation of the effective cell size.