To comprehensively investigate the impact of ethane (C2H6) on methane (CH4) explosions, a standard test device for the flammable limits of combustible gases was used to examine the influence of C2H6 on the CH4 explosion parameters with nitrogen dilution. The flammable limits for CH4 in air and under a nitrogen atmosphere in the presence of C2H6 were obtained. Additionally, the critical index behaviors were analyzed, and the CH4 explosive triangles at different operating modes were drawn. Using the explosive diagrams, the effects of C2H6 on the location and area of the CH4 explosive triangle were analyzed. Both the lower and upper flammable limits were reduced by the addition of C2H6. Simultaneously, the explosive hazard degree (F value) increased. Furthermore, the inerting nitrogen concentration at the converging point for the CH4 explosion linearly increased with the increase in C2H6, whereas the explosive oxygen concentration decreased. The CH4 explosive triangle expanded and shifted to the left bottom corner in the presence of C2H6. The area of the explosible zone increased, while that of the no explosion zone decreased. Meanwhile, the ratio of the inert gas and combustible gas required to depress the explosion significantly increased, and more inert gas was required to maintain CH4 in a completely inert state.