Five different calibrations of metal abundances of globular clusters are examined and these are compared with metallicity ranking parameters such as ( S p ) c , . Q39 and IR-indices. Except for the calibration [ F e / H ] H by the high dispersion echelle analysis. the other calibration scales are correlated with the morphological parameters of red giant branch. In the [ F e / H ] H -scale. the clusters later than ∼ F 8 have nearly a constant metal abundance. [ F e / H ] H ≃ − 1.05 , regradless of morphological characteristics of horizontal branch and red giant branch. By the two fundamental calibration scales of [ F e / H ] L (derived by the low dispersion analysis) and [ F e / H ] Δ s (derived by the spectral analysis of RR Lyrae stars). the globular clusters are divided into the halo clusters with [Fe/H]<-1.0 and the disk clusters confined within the galactocentric distance τ G = 10 k p c and galactic plane distance |z|=3 kpc. In this case the abundance gradient is given by d[Fe/H]/ d r G ≈ − 0.05 k p c − 1 and d[Fe/H]/ d | z | ≃ − 0.08 k p c − 1 within τ G = 20 k p c and |z|=10 kpc, respectively. According to these characteristics of the spatial distribution of globular clusters. the chemical evolution of the galactic globular clusters can be accounted for by the two-zone (disk-halo) slow collapse model when the [ F e / H ] L -or [ F e / H ] Δ s -scale is applied. In the case of [ F e / H ] H -scale, the one-zone fast collapse model is preferred for the evolution of globular clusters.