  Sky locating massive black hole binaries (MBHBs) from the foreground of
double white dwarf (DWD) is essential for space-based gravitational wave (GW)
detection. In an orbit period of the space crafts, there is an optimal orbital
position of the GW detectors to observe GW sources, where the signal intensity
is at its peak. From the model Q3-d, five MBHB sources are selected based on
the optimal observation orbital positions of the GW detectors, which are
associated with the orientation of the MBHB perpendicular to the detection
arms. For two MBHB sources of lower intensity, luminosity distance
uncertainties, $\Delta D_L$/$D_L$ at the 95$\%$ confidence level from the
overlapping GW signals of MBHB and DWD sources, when employing wavelet
decomposition and reconstruction methods, are improved by $\sim$ 2 times and
$\sim$ 10 times. Besides, the angular resolutions $\Delta \Omega_s$ are also
improved by a factor of $\sim$ 35 and $\sim$ 8. These results imply that we can
obtain relatively high accuracy of quickly localizing MBHB from the overlapped
GW signals with DWDs at the best observation orbit position. The luminosity
distance uncertainties at the 95$\%$ confidence level for MBHB sources with the
higher sign-noise ratio, have constraints on the precision of the Hubble
constant.
