guiding principle
noun [ C ] uk/ˌɡaɪ.dɪŋ ˈprɪn.sə.pəl/ us/ˌɡaɪ.dɪŋ ˈprɪn.sə.pəl/
指导思想，指导原则
an idea that influences you very much when making a decision or considering a matter
Equality of opportunity has been the government's guiding principle in its education reforms. “机会均等”一直是这个国家教育改革的指导原则。