  In this paper, we present the two-loop correction to scattering amplitudes in
three-dimensional $\mathcal{N}=6$ Chern-Simons matter theory. We use
eight-point case as our main example, but the method generalizes to all
multiplicities. The integrand is completely fixed by dual conformal symmetry,
maximal cuts, constraints from soft-collinear behavior and from vanishing of
odd-multiplicity amplitudes. After performing integrations with Higgs
regularizations, the integrated results demonstrate that the infrared
divergence is again identical to that of ${\cal N}=4$ super Yang-Mills. After
subtracting divergences, the finite part is dual conformal invariant, and
respects various symmetries; it has uniform transcendentality weight two and
exhibits nice analytic structure.
