  In an earlier work we developed a holographic theory for the phase transition
between bosonic symmetry-protected topological (SPT) states. This paper is a
continuation of it. Here we present the holographic theory for fermionic SPT
phase transitions. We show that in any dimension $ d $, the critical states of
fermionic SPT phase transitions has an emergent $Z_2^T$ symmetry and can be
realized on the boundary of a $ d+1 $-dimensional bulk SPT with an extra
$Z_2^T$ symmetry.
