  The typical blazar S5 0716$+$714 is very interesting due to its rapid and
large amplitude variability and high duty cycle of micro-variability in optical
band. We analyze the observations in I, R and V bands obtained with the $1.0m$
telescope at Weihai observatory of Shandong University from 2011 to 2018. The
model of synchrotron radiation from turbulent cells in a jet has been proposed
as a mechanism for explaining micro-variability seen in blazar light curves.
Parameters such as the sizes of turbulent cells, the enhanced particle
densities, and the location of the turbulent cells in the jet can be studied
using this model. The model predicts a time lag between variations as observed
in different frequency bands. Automatic model fitting method for
micro-variability is developed, and the fitting results of our multi-frequency
micro-variability observations support the model. The results show that both
the amplitude and duration of flares decomposed from the micro-variability
light curves confirm to the log-normal distribution. The turbulent cell size is
within the range of about 5 to 55 AU, and the time lags of the
micro-variability flares between the I-R and R-V bands should be several
minutes. The time lags obtained from the turbulence model are consistent with
the fitting statistical results, and the time lags of flares are correlated
with the time lags of the whole light curve.
