The interaction of a three-level V-typeatom with a squeezed vacuum is analyzed. The effect of quantum interference between decay processes from two upper levels on the spontaneous emission is studied. When the upper levels are degenerated, the strong interference has effect on the steady state of the atom and the spectrum of the fluorescent light, and results in the sensitivity to the initial state of the atom. In this case, squeezing results in the symmetry of the spectrum about the central frequency of the squeezed vacuum, but the interference results in the asymmetry of it.High-order harmonic spectra are obtained by numerically solving the one-dimensional time-dependent Schrodinger equation with single-active-electron (SAE) approximation. The time profiles of the harmonic spectra from a single atom are obtained through a Gabor analysis of the acceleration of the atomic dipole. The dependency of the different harmonics on the ground state population is investigated. It is shown that the harmonic yield tends to be saturated when driving laser is getting more and more intense, and that the harmonic radiation tends to be concentrated in a shorter interval when the harmonic order is getting higher, resulting in wider spectrum width.