Digital economy has become the new engine of national economic growth and high-quality economic development. The major issue facing the current system of national accounts is how to objectively, accurately and comprehensively calculate the scale of the digital economy and its contribution to economic growth. Based on the comparison of domestic and foreign digital economy accounting scopes and measurement methods, this article fully considers the activities of digital economy in china, and combines the actual situation of China’ s national economic industry classification to develop a digital economy classification system that meets China’s actual situation. This article uses the input-output analysis method to calculate the scale of the digital economy in 2017 to be 21. 42 trillion yuan, accounting for 26. 09% of GDP. Finally, the scale of the digital economy measured by related institutions is compared with the data measured in this article, and it is believed that the input- output analysis method has unique advantages in measuring the scale of the digital economy. This article looks forward to the follow-up research on digital economy accounting.