This article proposes a novel method to describing the chord relations involving triads and seventh chords. It is based on the quantity of semitones between two chords, while also considering the quantity of common tones and the quality and quantity of intervals beyond semitones and common tones. The premise of this research is that the existence of semitones and quantity of semitones between chords are correlated with the degree of tendency of their relation. After examining the effects of semitones, common tones, and other intervals between two chords, this article introduces a new concept called “Chord Relation Value” to facilitate a quantitative and qualitative analysis of chord relations. A key innovation of this study is its departure from traditional voice leading concepts by examining all possible semitonal movements between two chords, leading to conclusions that differ from those of existing analytical theories. Through the analysis of musical excerpts from various periods, including classical music, pop music, jazz music and film music, this article demonstrates that the Chord Relation Value is highly effective in analyzing and describing the chord relations involving triads and seventh chords, applicable in both tonal and non-tonal contexts.