There is usually a contradiction between increasing energy densities and reducing sensitivities of explosives. The explosives with both high energy densities and low sensitivities, or the so-called insensitive high explosives (IHEs), are desirable in most cases. It seems from applied explosives that amino groups are advantageous to IHE but the amount of amino groups contained IHEs is very limited. To make this clear, we present systemic examinations of the effects on the two properties stressed in IHEs after introducing amino groups to different molecular skeletons. As a result, the amino groups on resonant sites to nitro groups in conjugated systems can improve distinctly sensitivities and change energy densities in terms of oxygen balance; while the amino groups in unconjugated systems can hardly increase energy densities and usually cause increased sensitivities. It agrees well with a fact that almost all the molecules of applied amino group contained explosives possess conjugated skeletons. We therefore confirm that if amino groups are introduced resonantly to a nitro group in a conjugated system and the introduction improves OB, they are advantageous to IHEs.