Achieving common prosperity is the essential requirement of socialism and an important symbol of building a modern and powerful socialist country with Chinese characteristics. The key to solidly promoting common prosperity lies in promoting low-income group to increase their income，expanding the scale of middle-income group，eliminating the polarization of income distribution，gradually narrowing the income distribution gap，and realizing the transformation of income distribution structure from“pyramidal”to“olive”. However，the current income distribution in China is not optimistic，with the Gini coefficient of 0.468 in 2020，which is significantly higher than the international alert line of 0.4，and more than 60% of the residents do not reach the middle-income standard proposed by the National Bureau of Statistics. Narrowing the income gap and expanding the size of the middle-income group are important goals for China during the 14th Five-Year Plan. In the context of the disappearance of demographic dividend，demand contraction，supply shock and weakened expectations，how to achieve the expansion of the middle-income group is an urgent issue for us to consider and solve.
The digital economy as a new economic model provides a strong impetus for sustainable and healthy economic and social development，and while the country promotes the expansion of middle-income scale，it also emphasizes the need to actively promote the development of digital economy. During the 14th Five-Year Plan period，the digital economy should shift to a new stage of deepening application，standardizing development and sharing for the benefit of all，and continue to promote profound changes in the modes of production，life and governance.Can the inclusive sharing of digital economy alleviate the problem of insufficient income growth of low-income group，promote their upward mobility and expand the middle-income group？ To address these questions，the article theoretically analyzes the characteristics of each income class and the impact of digital economy development on the upward mobility of low-income groups' classes，and empirically tests them using data from the China Family Panel Studies（CFPS）.

The study finds that：First，as of 2018，68.67% of households in China are still in the low-income class，and the“pyramidal”income distribution structure is obvious，and the upward mobility of the low-income class is slow；Second，the development of digital economy promotes the upward mobility of the low-income group and helps to expand the middle-income group；Third，the mechanism test finds that household entrepreneurship，financial participation and employment level are important channels through which the digital economy promotes the upward mobility of low-income group；Fourth，heterogeneity analysis finds that the boosting effect of digital economy development on upward mobility of income classes of low-income group is more pronounced in the central and western regions and in regions with lower levels of economic development，and that this boosting effect is stronger among rural households and high human capital households compared to urban and low human capital households. The findings of the article provide new arguments for digital economic development to promote common prosperity