In order to study the high-order harmonic emission process in metal nanostructure, the high-order harmonic generation from He+ in bowtie-shaped metal nanostructure is theoretically investigated by solving time-dependent Schrdinger equation. Results show that in bowtie-shaped metal nanostructure, the harmonic radiation cut-off frequency can be extended when the spatial position of He+ is away from the nanostructure gap center. The harmonic cut-off frequency is mainly generated by the positive (negative) parts of laser when He+ is moving away from the gap center of nanostructure along the positive (negative) directions. Due to the limited gap size of metal nanostructure, the maximum cutoff frequency can be found in some specific spatial position of He+. With the control of two-color field, the harmonic spectrum shows a 333 eV super-continuum platform region. By superimposing the harmonics of the platform region, ultrashort ultraviolet pulses with pulse widths ranging from 25 as to 28 as can be obtained.