Summary: We investigate the edge-toughness of some regular graphs. It is proved that, for a noncomplete connected \(r\)-regular graph with \(r=\mathcal{K}'(G)\), its edge-toughness approximately equals \(\dfrac r2 \left(1+\dfrac1{|V(G)|-1}\right)\). The formulae for estimating the edge-toughness of Cartesian product and Kronecker product of some special graphs are presented.