Objective This paper introduces a method for determining the calorific value of natural gas by using the correlation of sound velocity and visible light spectrum, so that domestic natural gas quality detection and energy measurement workers and enterprises can more effectively carry out the research and standardization of this method, and provide more diversified choices for the determination methods of calorific value of natural gas. Methods Based on the comparative analysis of the advantages and disadvantages of various natural gas calorific value determination methods and related standards, the method principle of using sound velocity and visible light spectrum correlation to determine the calorific value of natural gas is introduced, and the calorific value data of a group of gas reference materials determined by gas chromatography and the introduced correlation method are analyzed. Results The measured value of calorific value of natural gas determined by the correlation between sound velocity and visible light spectrum is in good agreement with the calculated value according to GB/T 11062-2020 Natural gas-Calculation of calorific values, density, relative density and Wobbe indices from composition. For six binary gas reference materials simulating natural gas, the relative deviation is between 0.08%-0.42%; For five kinds of multi-component (up to 14 components) gas reference materials simulating natural gas, the relative deviation is-0.45%-0.07%. Conclusions The feasibility of measuring the calorific value of natural gas by using the correlation between sound velocity and visible light spectrum is preliminarily verified. This method has the characteristics and advantages that multiple data can be obtained within 1 s, synchronized with flow measurement, and the measurement is not limited by gas components and not effected by H2. It is suggested to further carry out the research on accuracy, measurement range, precision and field application, and timely establish standard methods, level 0 test devices of calorific value direct combustion, gas compression factor, density and other test devices. [ABSTRACT FROM AUTHOR]