This paper focused on configuration of matrix cracks for plain-woven CF/Epoxy composites under cyclic loading. Load-controlled fatigue tests were conducted under tension-tension cyclic loads at a stress ratio R of 0.1 and a frequency of 5 Hz in the laboratory condition. The number and the location of matrix cracks were observed for the damaged specimen by using an optical micro-scope. The modulus reduction ratio was continuously measured during fatigue tests. The experimental results showed that the configuration of matrix cracks was quantitatively estimated with the number of matrix cracks and statistical parameters (configurational coefficient and average distance between cracks). For parallel-sided specimens, the average distance between cracks became shorter with an increase of number of matrix cracks. It was found that the relationship between configurational coefficient and the modulus reduction ratio was linear.