In this paper the matrix expressions of equivalent points of microcosmic symmetrygroups of crystal unit spaces and their corresponding reciprocal spaces are applied in the dis-cussion of the systematic absence law of the crystal's X-ray diffraction. The universallyvalid algebraic formulas for the systematic absence law for all space groups are establishedand proved. That is, an arbitrary point h of all systematic absence points of the correspond-ing reciprocal space of every crystal unit space must satisfy a certain group of the listed belowtwo...
