In order to obtain attosecond pulses in X-ray range, the method of generating high intensity harmonic spectra and attosecond pulses by combining ultraviolet and chirped laser beams was introduced. The theoretical analysis was carried out. The results show that, when forward chirp parameter is introduced, harmonic cut-off energy has a slight extension and the efficiency of harmonic radiation decreases significantly. When negative chirp parameter is introduced, harmonic cut-off energy is extended and harmonic radiation efficiency is enhanced under the condition of forward chirp. When a 125nm ultraviolet light source is introduced into the chirped laser, the efficiency of harmonic radiation is obviously enhanced because of the effect of resonance-enhanced ionization. Driven by ultraviolet-forward chirp, harmonic radiation intensity is enhanced 25 times and harmonic cut-off energy is extended. A 382eV platform area is formed. Driven by ultraviolet-negative chirp, harmonic cut-off energy does not changed significantly but the efficiency of harmonic radiation is 110 times higher. A 410eV platform area is formed. By superposing the harmonics in the combined field, a series of single attosecond pulses within 70as can be obtained. This study is helpful for the development of attosecond science.