  We study the X-ray phases of the Crab pulsar utilizing the 11-year
observations from the Rossi X-ray Timing Explorer, 6-year radio observations
from the Nanshan Telescope, and the ephemeris from Jodrell Bank Observatory. It
is found that the X-ray phases in different energy bands and the radio phases
from Nanshan Telescope show similar behaviors, including long-time evolution
and short-time variations. Such strong correlations between the X-ray and radio
phases imply that the radio and X-ray timing noises are both generated from the
pulsar spin that cannot be well described by the the monthly ephemeris from the
Jodrell Bank observatory. When using the Nanshan phases as references to study
the X-ray timing noise, it has a significantly smaller variation amplitude and
shows no long-time evolution, with a change rate of $(-1.1\pm1.1)\times10^{-7}$
periods per day. These results show that the distance of the X-ray and radio
emission regions on the Crab pulsar has no detectable secular change, and it is
unlikely that timing-noises resulted from any unique physical processes in the
radio or X-ray emitting regions. The similar behaviors of the X-ray and radio
timing noises also imply that the variation of the interstellar medium is not
the origin of the Crab pulsar's timing noises, which is consistent with the
results obtained from the multi-frequency radio observations of PSR B1540-06.
