  Although it is acknowledged that GRB redshift is cosmological at present, but
it in fact has never been confirmed. However, the fact is still unclear because
which may be cosmological redshift (including possibly the host galaxy redshift
or the background galaxy redshift) or the redshift results from gravity of
neutron star; in other words, GRB redshift may be related to its distance or
not. Here, I enumerate a series of evidences, including three methods, to
determine whether the GRB distance does depend on the redshift. Firstly, the
correlation analysis shows that there is no correlation between the fluence of
131 GRBs (and the 1 s peak photon flux of 111 GRBs) and the redshift although
there is a significant correlation between the apparent magnitude of 32 hosts
and the redshift. Secondly, from the number-redshift relation of GRBs and the
deductive reasoning, one can deduce an absurd conclusion that the probability
of a nearby galaxy generating a GRB event would vary inversely as its distance
square if GRB indeed comes from an external galaxy and the distance depends on
the redshift. Thirdly, if the distance is related to the redshift, then the
variables of fluence and peak flux definitely cannot be separated from the
variable of redshift in distribution functions of both the fluence-redshift and
the peak flux-redshift; while the variables separation tests show that they in
effect do, and we then can exactly forecast the values of the fluence and the
peak flux for the GRBs with redshift z > 4.5. Other evidences all show that GRB
distance is independent from the redshift without exception.
