[Objective] To find out a suitable straw returning mode for the rice-wheat rotation ecosystem with high yield in Chengdu Plain, and to offer a scientific basis for the efficient operation of regional farmland system.[Methods] Four treatments in field experiment was designed according to applied straw quantities, i.e., chemical fertilizer only(CF), chemical fertilizer plus a half of straw returning(CFS₁), chemical fertilizer plus total straw returning(CFS₂), chemical fertilizer plus 1.5 times of straw returning(CFS₃). Based on emergy analysis method, we studied the changes of total amount of emergy input and output, the structure of emergy input and output and the emergy indexes among different fertilization treatments.[Results] (1) The results showed that, as compared to CF mode, other straw returning modes lowered the proportion of the non-renewable industrial assistant emergy to the total emergy input and increased the level of self-supply ability and the total emergy output. (2) From the perspective of the emergy indexes, as compared to the CF mode, straw returning modes had higher levels of net emergy yield ratio, emergy input ratio, emergy feedback ratio, emergy productivity and emergy-labor productivity, and had lower levels of environmental load ratio. Straw returning modes effectively improve the sustainable development ability of farmland system, especially CFS₂ and CFS₃ modes had the lower environmental load ratio and the higher emergy sustainable index.[Conclusion] Modes of CFS₂ and CFS₃ are the suitable straw returning modes under a rice-wheat rotation in Chengdu Plain.