The present article discusses the provision of metrological support for measuring liquid mass and volume in a flow, as well as liquid mass and volumetric flow rates within the microflow range of 10−5 to 103 mL/min, to satisfy needs of leading sectors of the world economy. Drawing on an analytical review, the main metrological and performance characteristics of national standards are presented. The article uses the dynamic weighing method to outline the basic principles of flow generation in national gravimetric and volumetric standards during liquid mass and volume measurements. The design and operating principles of key modules available in national standards are considered. Methods for supplying liquids to collection vessels and their design are described, taking into account the necessity to minimize liquid evaporation, as well as the impact of capillary force and buoyancy. The primary sources of uncertainty in measuring the mass and volume of liquid using the dynamic weighing method are considered, along with methods for minimizing such uncertainties. A modified model for the dynamic measurement of liquid mass flow rate is proposed, which takes the primary sources of uncertainty into account. The influence of various sources of uncertainty on the metrological characteristics of national standards is discussed.