Ruling country in accordance with laws and regulations, and constructing socialist legal ruling country, are our country developing aims ahead. What is the content on earth which socialist legal rule includes is the key point to properly comprehend and master the intension of ruling country in accordance with laws and regulations. This essay probes legal rule and legal system, legal rule and person rule, the essence of legal rule, and compares the relations between them, and on this basis, brings to light the fundamental intension of socialist legal rule, preliminarily puts forward the prior target of realizing socialist legal rule.