  Weyl fermions, first proposed for describing massless chiral Dirac fermions
in particle physics, have not been observed yet in experiments. Recently, much
effort has been devoted to explore Weyl fermions around band touching points of
single particle energy dispersions in certain solid state materials (named
\textit{Weyl semimetals}), similar as graphene for Dirac fermions. Here we show
that such Weyl semimetals also exist in the quasiparticle excitation spectrum
of a three-dimensional (3D) spin-orbit coupled Fulde-Ferrell (FF) superfluid.
By varying Zeeman fields, the properties of Weyl fermions, such as their
creation and annihilation, number and position, as well as anisotropic linear
dispersions around band touching points, can be tuned. We study the
manifestation of anisotropic Weyl fermions in sound speeds of FF fermionic
superfluids, which are detectable in experiments.
