  We present a quantum hyperdense coding protocol with hyperentanglement in
polarization and spatial-mode degrees of freedom of photons first and then give
the details for a quantum secure direct communication (QSDC) protocol based on
this quantum hyperdense coding protocol. This QSDC protocol has the advantage
of having a higher capacity than the quantum communication protocols with a
qubit system. Compared with the QSDC protocol based on superdense coding with
$d$-dimensional systems, this QSDC protocol is more feasible as the preparation
of a high-dimension quantum system is more difficult than that of a two-level
quantum system at present.
