The analytic expressions of the Helmholtz free energy, the Gibbs thermodynamic potential the mean nearest neighbor distance between two atoms, the crystal parameters for bcc, fcc and hcp phases of defective and perfect substitutional alloys AB with interstitial atoms C and structural phase transition temperatures of these alloys at zero pressure and under pressure are derived by the statistical moment method. The structural phase transition temperatures of the main metal A, the substitutional alloy AB and the interstitial alloy AC are special cases of ones of the substitutional alloy AB with interstitial atoms C