We introduce the notion of weak dually residuated lattice ordered semigroups (WDRL-semigroups) and investigate the relation between $R_0$-algebras and WDRL-semigroups. We prove that the category of $R_0$-algebras is equivalent to the category of some bounded WDRL-semigroups. Moreover, the connection between WDRL-semigroups and DRL-semigroups is studied.