  Full-disk spectroscopic observations of the solar corona are highly desired
to forecast solar eruptions and their impact on planets and to uncover the
origin of solar wind. In this paper, we introduce a new multi-slit design (5
slits) to obtain extreme ultraviolet (EUV) spectra simultaneously. The selected
spectrometer wavelength range (184-197 \r{A}) contains several bright EUV lines
that can be used for spectral diagnostics. The multi-slit approach offers an
unprecedented way to efficiently obtain the global spectral data but the
ambiguity from different slits should be resolved. Using a numerical simulation
of the global corona, we primarily concentrate on the optimization of the
disambiguation process, with the objective of extracting decomposed spectral
information of six primary lines. This subsequently facilitates a comprehensive
series of plasma diagnostics, including density (Fe XII 195.12/186.89 \r{A}),
Doppler velocity (Fe XII 193.51 \r{A}), line width (Fe XII 193.51 \r{A}) and
temperature diagnostics (Fe VIII 185.21 \r{A}, Fe X 184.54 \r{A}, Fe XI 188.22
\r{A}, Fe XII 193.51 \r{A}). We find a good agreement between the forward
modeling parameters and the inverted results at the initial eruption stage of a
coronal mass ejection, indicating the robustness of the decomposition method
and its immense potential for global monitoring of the solar corona.
