Based on the higher-order nonlinear Schrdinger equation describing the propagation of ultrashort pulses in negative-index materials, the interactions of bright and dark solitary waves in negative-index materials are studied using symmetrical Split-step Fourier method, respectively. Lots of numerical results show that when initial frequency shift is zero, the interactions between bright solitary waves are similar to those of bright solitons in conventional materials; when initial frequency shift is nonzero, the transmission speed and interactions are influenced by the third-order dispersion and the self-steepening effects. While the interactions between dark solitary waves are similar to those of dark solitary waves in conventional materials behaving repulsion each other under the influence of the third-order dispersion and the self-steepening effects whether initial frequency shift is zero or not. The results show that the interactions of bright and dark solitary waves in negative-index materials may be suppressed to some extent. The obtained results provide a theoretical basis for the applications of negative-index materials in future high-speed communication.