Abstract: At current, China's water environment management is faced with the problem that pollution sources are difficult to be identified quickly and accurately. Aqueous fingerprint traceability through the measurement of three-dimensional fluorescence spectrum of pollutants, the resulting aqueous fingerprint can be compared with the pollution source database, and therefore quickly and accurately identify the discharge source. This paper takes aqueous fingerprint traceability as a case study, through the field investigation of a water environment laboratory, from the perspective of objectivity to open the “black box” of scientific measurement. The pilot application of the technology is essentially a gradual process of the laboratory constructing the objectivity of scientific measurements. Measurement can be regarded as the production of quantitative values, The laboratory constructed the absolute objectivity, local objectivity and interactive objectivity of aqueous fingerprint traceability at three levels: the selection of measurement methods, the development of measurement standards and the interpretation of measurement results. The technology is widely accepted and recognized, with success in pilot applications.