  Using high spatial and temporal data from the \emph{Solar Dynamics
Observatory} (\emph{SDO}) and the \emph{Interface Region Imaging Spectrograph}
(\emph{IRIS}), several observational signatures of magnetic reconnection in the
course of magnetic flux cancellation are presented, including two loop-loop
interaction processes, multiple plasma blob ejections, and a sheet-like
structure that appeared above the flux cancellation sites with a Y-shaped and
an inverted Y-shaped ends. The \emph{IRIS} 1400 \AA\ observations show that the
plasma blobs were ejected from the tip of the Y-shaped ends of the sheet-like
structure. Obvious photospheric magnetic flux cancellation occurred after the
first loop-loop interaction and continued until the end of the observation.
Complemented by the nonlinear force-free field extrapolation, we found that two
sets of magnetic field lines, which reveal an X-shaped configuration, align
well with the interacted coronal loops. Moreover, a magnetic null point is
found to be situated at about $0.9$ Mm height right above the flux cancellation
sites and located between the two sets of magnetic field lines. These results
suggest that the flux cancellation might be a result of submergence of magnetic
field lines following magnetic reconnection that occurs in the lower atmosphere
of the Sun, and the ejected plasma blobs should be plasmoids created in the
sheet-like structure due to the tearing-mode instability. This observation
reveals detailed magnetic field structure and dynamic process above the flux
cancellation sites and will help us to understand magnetic reconnection in the
lower atmosphere of the Sun.
