  High precision CCD observations of six totally eclipsing contact binaries
were presented and analyzed. It is found that only one target is an A-type
contact binary (V429 Cam), while the others are W-type contact ones. By
analyzing the times of light minima, we discovered that two of them exhibit
secular period increase while three manifest long-term period decrease. For
V1033 Her, a cyclic variation superimposed on the long-term increase was
discovered. By comparing the Gaia distances with those calculated by the
absolute parameters of 173 contact binaries, we found that Gaia distance can be
applied to estimate absolute parameters for most contact binaries. The absolute
parameters of our six targets were estimated by using their Gaia distances. The
evolutionary status of contact binaries was studied, we found that the A- and
W- subtype contact binaries may have different formation channels. The
relationship between the spectroscopic and photometric mass ratios for 101
contact binaries was presented. It is discovered that the photometric mass
ratios are in good agreement with the spectroscopic ones for almost all the
totally eclipsing systems, which is corresponding to the results derived by
Pribulla et al. and Terrell & Wilson.
