  We present the optical spectroscopic observations of X Per from 1999 to 2013
with the 2.16m telescope at Xinglong Station and the 2.4m telescope at Lijiang
station, National Astronomical Observatories of China. Combining with the
public optical photometric data, we find certain epochs of anti-correlations
between the optical brightness and the intensity of the H{\alpha} and HeI 6678
lines, which may be attributed to the mass ejections from the Be star.
Alternative explanations are however also possible. The variability of FeII
6317 line in the spectra of X Per might be also caused by the shocked waves
formed after the mass ejections from the Be star. The X-ray activities of the
system might also be connected with the mass ejection events from the Be star.
When the ejected materials were transported from the surface of the Be star to
the orbit of neutron star, an X-ray flare could be observed in its X-ray light
curves. We use the neutron star as a probe to constrain the motion of the
ejected material in the circumstellar disk. With the diffusion time of the
ejected material from the surface of Be star to the orbit of neutron star, the
viscosity parameter {\alpha} of the circumstellar disk is estimated to be 0.39
and 0.28 for the different time, indicating that the disk around Be star may be
truncated by the neutron star at the 2:1 resonance radius and Type I X-ray
outburst is unlikely to be observed in X Per.
