Abstract: Strength is closely reated to microstructure. In this paper, microstructure was subdivided into very small blocks called phase quanta and consequenty any microstructure may be produced by different arrangements of these phase quanta. In this way statistical method will be applicable. to derive the relation between strength and morphology of phase. It was found that the distribution function of phase quanta is eimilar to Gauss type, and a relation between strength and structural parameters was finally established. This relation hold true when confirmed with published data. Comparisons with some previous theories were also discussed.