Recent NMR study of high-T-C superconductors carried out by Osaka grou
p is reviewed. NQR frequency nu(Q). Knight shift K, T-1 of Cu-63 and O
-17 were measured over a wide hole doping range from light- to heavy-d
oped systems, LSCO, YBCO, HBCCO, BSCCO, TBCCO and TBCO, together with
impurity and pressure effect. By analysing nu(Q), K and T-1, the local
hole numbers of Cu and O at the CuO2 plane, n(Cu) and n(O) the relati
ve magnitude of the uniform susceptibility, chi(0) and the low-frequen
cy component of the antiferromagnetic spin fluctuations (AFSF), chi(Q)
/Gamma (chi(Q) is the staggered susceptibility and Gamma is the charac
teristic energy of the spin fluctuation at q = 0) are obtained. The re
lation between n(Cu), n(O) and chi(Q), chi(Q)/Gamma, T-C, etc. were di
scussed. There are optimum values of n(Cu)/2n(O) and n(Cu) + 2n(O) to
give maximum T-C. The NMR results in the superconducting state are wel
l-explained by d-wave pairing model. The result is consistent with the
AFSF mediated superconducting model.