In this article, we study the properties of endomorphism ring of FI-semi injective modules. As a result, we observed that, finite-dimensional FI-Semi injective module has a semi local endomorphism ring and endomorphism ring of an epi-retractable R-module M, whose submodules are FI-M-principally injective, is right principally projective. Further we prove that, extending FI-semi-injective module M is co-Hopfian if and only if it satisfies the cancellation property.