  Motivated by the latest LHC Higgs data, we calculate the new physics
contributions to the Higgs decay channels of $h\to \gamma\gamma, Z\gamma,
\tau\tau, WW^*$ and $ ZZ^*$ in the left-right twin Higgs (LRTH) model, induced
by the loops involving the heavy T-quark, the $W_H$ and $\phi^\pm$ bosons
appeared in the LRTH model. We find that (a) for a SM-like Higgs boson around
125.5 GeV, the signal rates normalized to the corresponding standard model (SM)
predictions are always suppressed when new physics contributions are taken into
account and approach the SM predictions for a large scalar parameter $f$; and
(b) the LRTH prediction for $R_{\gamma\gamma}$ agree well with the CMS
measurement $R_{\gamma\gamma}=0.77\pm 0.27$ at $1\sigma$ level, but differ with
the ATLAS result. The forthcoming precision measurement of the diphoton signal
at the LHC can be a sensitive probe for the LRTH model.
