The in-situ ¹³CO₂ pulse labeling technique was used to trace the fate of ¹³C in maize-soil system and asses the effect of fertilization and plastic film mulching on the dynamics of photosynthetically fixed carbon by maize planted in the long-term Brown Earth Experiment Station in Shenyang Agricultural University. Results show that the carbons were quickly translocated and distributed unevenly in the maize-soil system on D 1 (the first day after labeling), showing an order of shoots > roots > rhizosphere soil > bulk soil, and unmulched > mulched in δ¹³C value. The δ¹³C values declined in maize plants and rhizosphere soil, but slightly increased in bulk soil with the time passing by from D 1 to D 15. Treatment CK was the highest in ¹³C enrichment with average δ¹³C value in shoots and roots reaching 1 568‰ and 598‰, respectively, on D 1 and 178‰ and 147‰, respectively, on D 15. The ¹³C fixed in the maize plants accounted for 64.01% of the total in the system on D 1 and for 38.65% on D 15. The distribution of ¹³C showed a declining trend in the order of shoots > roots > rhizosphere soil > bulk soil in the plant-soil system. The experiment clearly demonstrated that the treatment of mulching plus organic manure significantly increased photosynthetical fixation of ¹³C and the allocation of ¹³C in maize plant and soil, which means that it is an important practice to improve carbon assimilation and distribution in the maize-soil system.