Plastic film mulching is an important agricultural practice to improve crop yields and ensure sufficient food supply for the growing population. But the improvements in soil moisture and temperature under plastic film mulching stimulate the mineralization and loss of soil organic carbon. Any increase in crop yields must not be at the expense of soil quality. Studying the sequestration characteristics of newly added carbon and nitrogen in Mollisol's aggregates after plastic film mulching is crucial for the sustainable application of plastic film mulching. We collected topsoil samples (0-20 cm) from three fertilization treatments (no fertilization application, CK; inorganic fertilizer, NPK; and inorganic fertilizer plus manure, MNPK) at a 29-year long-term Mollisol experiment in Northeast China. We then mixed three fertilized soil samples with ¹³C¹⁵N double-labeled maize straw, and conducted a 900-day in-situ micro-plot incubation experiment without (bare) and with plastic film mulching. The objective of this study was to understand how plastic film mulching modified the dynamics of straw residue carbon and nitrogen incorporation into soil aggregates under various fertilizer management strategies. The results showed that compared with Mollisols of three fertilizer management strategies under bare conditions, plastic film mulching decreased straw residue carbon and nitrogen contents by 26.49% and 32.05% among the microaggregates (<0.25 mm), respectively. As for the MNPK treatment under bare conditions, plastic film mulching significantly decreased straw residue carbon and nitrogen contents by 35.58% and 15.97% in the macroaggregates (>0.25 mm), but increased native soil organic carbon content by 9.16% in the macroaggregates. Plastic film mulching increased the contribution percentage of straw residue carbon in organic carbon of the CK and NPK treatments among the microaggregates, when compared to that of corresponding bare conditions. But in macroaggregates and microaggregates of the MNPK treatment, the contribution percentage of straw residue carbon in organic carbon was significantly lower under plastic film mulching conditions than that under bare conditions. Regardless of bare or plastic film mulching, the contribution percentage of straw residue carbon in organic carbon and straw residue nitrogen in total nitrogen in macroaggregates and microaggregates were affected by fertilizer management strategies, and the contribution percentage of straw residue carbon and straw residue nitrogen in both aggregates decreased in the order of CK > NPK > MNPK. Moreover, the contribution percentage of straw residue carbon in organic carbon and straw residue nitrogen in total nitrogen in microaggregates were larger than those in macroaggregates. Overall, plastic film mulching promoted the renewal of organic carbon in the microaggregates of the NPK treatment; while in the MNPK treatment, plastic film mulching accelerated the loss of straw residue carbon and nitrogen in macroaggregates and microaggregates, it also played a positive feedback effect on the accumulation of native soil organic carbon among the macroaggregates.