  We use observational data from Type Ia Supernovae (SN), Baryon Acoustic
Oscillations (BAO), Cosmic Microwave Background (CMB) and observational Hubble
data (OHD), and the Markov Chain Monte Carlo (MCMC) method, to constrain the
cosmological scenario of holographic dark energy with varying gravitational
constant. We consider both flat and non-flat background geometry, and we
present the corresponding constraints and contour-plots of the model
parameters. We conclude that the scenario is compatible with observations. In
1$\sigma$ we find $\Omega_{\Lambda0}=0.72^{+0.03}_{-0.03}$,
$\Omega_{k0}=-0.0013^{+0.0130}_{-0.0040}$, $c=0.80^{+0.19}_{-0.14}$ and
$\Delta_G\equiv G'/G=-0.0025^{+0.0080}_{-0.0050}$, while for the present value
of the dark energy equation-of-state parameter we obtain
$w_0=-1.04^{+0.15}_{-0.20}$.
