  We study the effects of momentum relaxation on the holographic Weyl semimetal
which exhibits a topological quantum phase transition between the Weyl
semimetal phase and a topological trivial phase. The conservation of momentum
in the field theory is broken by the axion fields in holography. The
topological Weyl semimetal phase is characterized by a nontrivial anomalous
Hall conductivity. We find that the critical value of the phase transition
decreases when we increase the momentum relaxation strength up to a special
value, above which it goes to zero. This indicates that the Weyl semimetal
phase shrinks and finally disappears as the momentum relaxation strength is
increased, which is consistent with the weakly coupled field theory
predictions. We also study the behavior of transverse/longitudinal
conductivities and low temperature dependence of the d.c.resistivities with
respect to momentum relaxation strength.
