'Qín Jìn zhī hǎo' literally means 'the good relationship between the states of Qin and Jin.' It originates from the Spring and Autumn period (770–476 BCE), when the powerful neighboring states of Qin and Jin repeatedly formed marriage alliances to strengthen political ties—often marrying princes and princesses across state lines. The phrase uses 'Qin' and 'Jin' as proper nouns representing the two states, 'zhī' as a classical possessive particle ('of'), and 'hǎo' meaning 'good' or 'harmonious relationship.'

Today, it is used exclusively in formal or literary contexts to refer to a marital alliance between two families, organizations, or even nations—not just any friendly relationship, but one cemented by marriage for strategic unity. It carries connotations of diplomacy, mutual benefit, and long-term cooperation, and is often invoked in speeches, historical writing, or news commentary about international partnerships.