  Using the archive data from the Rossi X-ray Timing Explorer ({\sl RXTE}), we
have studied the evolution of the X-ray profile of the Crab pulsar in a time
span of 11 years. The X-ray profiles, as characterized by a few parameters,
changed slightly but significantly in these years: the separation of the two
peaks increased with a rate $0.88\pm0.20\,\textordmasculine$\,per century, the
flux ratio of the second pulse to the first pulse decreased with
$(3.64\pm0.86)\times10^{-2}$\,per century, and the pulse widths of the two
pulses descended with $1.44\pm0.15\,\textordmasculine$\, and
$1.09\pm0.73\,\textordmasculine$\,per century, respectively. The evolutionary
trends of the above parameters are similar to the radio results, but the values
are different. We briefly discussed the constraints of these X-ray properties
on the geometry of the emission region of this pulsar.
