This article examines the rise and decline of the enthusiasm for intelligence testing in early twentieth-century China, focusing on the appeal, the challenges, and the critiques revolving around this psychological instrument. The introduction of intelligence testing reflected not only China's urgent needs in modernizing its merit system, but also Chinese psychologists' aspirations for pursuing exactitude and redefining the racial characteristics of their compatriots against foreign interpretations. But despite psychologists' endeavors, the political and geographical fragmentation of Republican China troubled the epistemic imperative of uniformity demanded by Euro-American psychometrics and therefore undermined the validity of measurement. Subsequently, the legitimacy of intelligence testing began to be questioned by several influential Chinese psychologists in the late 1920s and 30s. The difficulties in standardization and the hostility within the psychology community formed a vicious cycle, impeding the progress of nationwide testing. Through this history, the article demonstrates not only the elevation of measurement to epistemic authority in modern China, but also how its promise was challenged by a diverse and rapidly changing society.