  The form factors in the radiative decay of $J/\psi$ to a scalar glueball are
studied within quenched lattice QCD on anisotropic lattices. The continuum
extrapolation is carried out by using two different lattice spacings. With the
results of these form factors, the partial width of $J/\psi$ radiatively
decaying into the pure gauge scalar glueball is predicted to be 0.35(8) keV,
which corresponds to a branching ratio of 3.8(9)x10^{-3}. By comparing with the
experiments, out results indicate that f_0(1710) has a larger overlap with the
pure gauge glueball than other related scalar mesons.
