Straw returning with decomposing inoculants was known to increase crop yield and promote soil fertility by accelerating straw decomposition and nutrient release of crop straw.A field experiment was conducted to investigate and compare the potassium accumulation,utilization efficiency and yield of rice under 4 treatments,including formula fertilization without potassium(N-P2O5-K2O=270-90-0 kg·hm-2)(T1),formula fertilization(N-P2O5-K2O=270-90-135 kg·hm-2)(T2),formula fertilization(N-P2O5-K2O=270-90-135 kg·hm-2)+straw returning(T3),formula fertilization(N-P2O5-K2O=270-90-135 kg·hm-2)+straw returning+decomposing inoculants(T4).The results showed that:(1) the total and net accumulation of potassium in rice under straw returning treatment increased by 15.3%and 13.9%,respectively,compared to formula fertilization treatment at the heading stage.While the content,the potassium content in rice were increased by 5.5%,total and net accumulation of potassium in rice were increased by 21.5%and 50%,respectively,at the maturing stage.(2)Compared with the treatments of formula fertilization,treatments of straw returning with and without decomposing inoculants increased rice yields by 6.4%and 10.4%,respectively.(3) In comparison to formula fertilization,the contribution rate,agronomic use efficiency,partial fertilizer productivity and absorption efficiency of potassium fertilizer in rice under straw returning and decomposing inoculants application increased by 9.2%，45.5%，10.4%and 39.0%,respectively.In conclusion,the results of this study indicated that straw returning with decomposing inoculants could increase the absorption and utilization efficiency of potassium as well as grain yields of rice,which might supply theoretical basis for straw application and fertilizer reduction.