  The power spectrum of transmitted flux in the Ly$\alpha$ forest in spectra of
distant quasars gives us an information about matter power spectrum on the
smallest spatial scales which is very important for testing of different models
of dark matter. Only a few independent samples of spectra obtained on diferent
instruments have been used for this purpose, thus using of additional
independent sample is useful for verification an existing results. We used the
data from the 2dF (Two-degree Field) QSO Redshift Survey (2QZ) to obtain the
mean transmitted flux for three different redshift bins. After visual
inspection and rejection of spectra with broad absorption lines, damped
Ly$\alpha$ systems and low signal-to-noise ratio spectra our final sample
contains 655 quasars with redshift range 2.3 $<z<$ 2.9. We present the results
on composite spectra, determination of continuum level for different redshift
ranges and the mean transmission in the Ly$\alpha$ forest as a function of
redshift within the range 2.1 $<z_{forest}<$ 2.5. The obtained
redshift-dependence of the mean transmission agrees well with the results of
other authors. These results can be used for calculation of the flux power
spectrum of Ly$\alpha$ forest.
