  We theoretically study the electron transport properties in a
ferromagnetic/normal/ferromagnetic tunnel junction, which is deposited on the
top of a topological surface. The conductance at the parallel (\textbf{P})
configuration can be much bigger than that at the antiparallel (\textbf{AP})
configuration. Compared \textbf{P} with \textbf{AP} configuration, there exists
a shift of phase which can be tuned by gate voltage. We find that the exchange
field weakly affects the conductance of carriers for \textbf{P} configuration
but can dramatically suppress the conductance of carriers for \textbf{AP}
configuration. This controllable electron transport implies anomalous
magnetoresistance in this topological spin valve, which may contribute to the
development of spintronics . In addition, we find that there is a
Fabry-Perot-like electron interference.
