  In this work we show that the supersymmetric economical SU(3)_C X SU(3)_L X
U(1)_X (3-3-1) gauge model has a realistic candidate for self-interacting dark
matter. In the model under consideration, the right-handed sneutrino is in
bottom of the triplet, which is a singlet of the Standard Model SU(2)_L group.
In addition, the right-handed sneutrino is the lightest slepton. By these
properties, the right-handed sneutrino is weakly interacting with the Standard
Model and stable without introduction of extra symmetry. From the
Spergel-Steinhardt condition, the typical mass limit $\leq 10 $ MeV is derived.
With self-interacting coupling constant fixed by supersymmetry, this limit is
deduced without any approximation. The condition for thermal generated
self-interacting dark matter in the Universe is also obtained.
