High-order harmonic emission and attosecond pulse generation from H+2 molecule driven by the spatial inhomogeneous laser field are theoretically investigated. Calculation results show that by properly adjusting the internuclear distance of H+2 molecule and spatial inhomogeneous parameters, the cutoff energy of harmonic emission is remarkably enhanced, and the interference structure of harmonic spectrum is also reduced. By introducing unipolar control laser field, the harmonic cutoff energy is further extended, and a 530 eV bandwidth long platform area contributed by a single quantum path is formed. By superposition of harmonics, a series of attosecond X-ray pulses with the pulse width ranging from 32 as to 46 as can be obtained.