The article analyzed the income differences between flexibly and nonflexibly employed persons based on the 2018 China Mobile Population Dynamics Monitoring Data, using OLS methods, propensity score matching (PSM), and Oaxaca-Blinder decomposition. The results show that the income of flexibly employed persons is 11.9%–23.6% higher than that of nonflexibly employed persons, with differences in individual endowment characteristics explaining 53.9% of the income difference and differences in coefficients of nonmarket factors explaining 45.7% of the income difference. The degree of income difference between the two groups in different industries varies; except for the primary industry, the secondary and tertiary industries all show higher income for flexibly employed persons than for nonflexibly employed persons. The difference in income between the two groups was as high as 25% or more in the sectors of “rental and business services,” “education,” and “culture, sports, and entertainment.” The high ratio of employers and self-employed workers in flexible employment and the fact that the average number of hours worked per week is 12.6 hours higher for flexible workers than for nonflexible workers are important factors contributing to the difference in earnings between these two groups. Clarifying the extent of the current income disparity between flexible and nonflexible employment groups and its sources, and formulating and adjusting relevant policies and measures in a timely manner are conducive to creating a fair and equitable labour market environment and promoting the healthy development of flexible employment under the new circumstances.