By using the angular spectrum and complex analytic signal representations, the analytic propagation expression and its Fourier spectrum for ultrashort Gaussian pulsed beams with constant waist width in the far field are derived. The far-field properties of few- and single-cycle ultrashort Gaussian pulsed beams with constant waist width are studied, and compared with those of ultrashort Gaussian pulsed beams with constant diffraction length. The properties of pulse broadening, spectrum narrowing, off-axis spectrum redshift and on-axis spectrum blueshift are found for ultrashort Gaussian pulsed beams with constant waist width in the far field.