This paper is devoted to the study of structure of Leibniz algebras. The classical methods to obtain classifications are essentially to solve a system of equations given by the identities of specified classes of algebras. In this work, some invariants were employed to obtain a complete list of three-dimensional Leibniz algebras over an arbitrary field  and it is applied to classify three-dimensional Leibniz algebras over  and

Leibniz algebra, classification, algorithm.