  We have calculated the cross section of $\psi'$ photoproduction at
small-$p_{T}$ regions in polarized $\gamma p$ collisions for testing the
color-octet model, which is based on NRQCD factorization formalism. We show
that the measurement of the two-spin asymmetry of this process might be
effective to constrain the value of NRQCD matrix elements.
