  For the constant-roll tachyon inflation, we derive the analytical expressions
for the scalar and tensor power spectra, the scalar and tensor spectral tilts
and the tensor to scalar ratio up to the first order by using the method of
Bessel function approximation. The derived $n_s-r$ results for the
constant-roll inflation are also compared with the observations, we find that
only one constant-roll inflation is consistent with the observations and
observations constrain the constant-roll inflation to be slow-roll inflation.
The tachyon potential is also reconstructed for the constant-roll inflation
which is consistent with the observations.
