  We explore the topological properties of non-Hermitian nodal-link semimetals
with dissipative cold atoms in a three-dimensional optical lattice. We
construct a two-band continuum model in three dimensions with a spin-dependent
gain and loss, where the exceptional points in the energy spectrum can comprise
a double Hopf link. The topology of the bulk band is characterized by a winding
number defined for a one-dimensional loop in the momentum space and a
topological transition of the nodal structures emerges as the change of the
non-Hermiticity strength. A non-Bloch theory is built to describe the
corresponding lattice model which has anomalous bulk-boundary correspondence.
Furthermore, we propose that the model can be realized using ultracold
fermionic atoms in an optical lattice and the exceptional nodal links as well
as the topological properties can be detected by measuring the atomic spin
textures.
