  The reason for the difference in the composite X-ray spectrum between
radio-loud quasars (RLQs) and radio-quiet quasars (RQQs) is still unclear. To
study this difference, we built a new composite X-ray spectrum of RLQs by using
Chandra X-ray data and Sloan Digital Sky Survey (SDSS) optical data for the
sample of 3CRR quasars. We find the X-ray spectra of all 3CRR quasars except
for 3C 351 have no soft X-ray excess and can be fitted with an absorbed
power-law model well. Our composite X-ray spectrum is similar to that of
\cite{ShangEtal2011apjs} for RLQs, showing higher hard X-ray and lower soft
X-ray flux than the composite X-ray spectrum of RQQs. Most blazar-like 3CRR
quasars have higher X-ray flux than the median composite X-ray spectrum, which
could be related to the contribution of beamed jet emission at X-ray band. From
the literature, we find that nineteen 3CRR quasars have extended X-ray emission
related to radio jets, indicating inevitable contribution of jets at X-ray
band. In contrast to RQQs, the X-ray photon index of 3CRR quasars does not
correlate with the Eddington ratio. Our results suggest that the jet emission
at X-ray band in RLQs could be related with the difference of composite X-ray
spectrum between RLQs and RQQs.

High Energy Astrophysical Phenomena