The origin and the regularity of the variation of hole concentration as well as the crystal structure and superconducting critical temperature versus the doping contents of Co for Cu (I) and Ca for Y in YBa2Cu3Oy are studied in this paper. The results reveal that the pattern in which the hole concentration in Cu-O sheets, Psh, is influenced greatly by the substitution depends upon the different substituting elements as well as the different atomic sites, e.g. the decrease of Psh in system substituted by Co for Cu (I) is from filling and localizing of holes, but the increase of Psh in system of Ca replacing for Y is due to the delocalization effect of the holes. When Y and Cu (1) are substituted simutaneously with Ca and Co respectively, the generation instead of the localization effect cf the holes is important for the change of Psh. In addition, the relationship between Psh and Tc is discussed.