Abstract: This article makes an inquiry into Ian Brownlie's objective positivist's view of international law in three aspects. Firstly, it deals with the general theory of international law embodied in his objective positivist point of views. His analysis has witnessed his acceptance of Kelsen's conception of "basic norms", but focused on the performance and efficacy of international law, holding that international law, to an extent misunderstood and underestimated in reality, is indeed effective more than what we have observed. Secondly, his method in treatment of customary international law is to test it in strict terms of constituent element state practice and opinio juris, the example of which is his dealing with the most controversial humanitarian intervention in international law. Thirdly, Brownlie has constructed the international public order in terms of "the rule of law in international affairs", the elements of which are of the nature of a formal conception of rule of law, quite distinct with the "policy-orientation approaches" of the "Yale School".