Abstract: In order to explore the united recycling approach of RD wet thermal decomposition of residual sludge and household garbage in sewage plant, the author used these 2 kinds of garbage as compost material, and conducted moderate temperature composting experiment added with potassium feldspar powder and K-releasing bacteria, studied potassium and phosphorous activity in 2 kinds of inoculation modes (I, II) compost system. The results showed that: (1) K-releasing bacteria separated from soil could convert insoluble potassium into soluble K in potassium feldspar powder in liquid batch culture experiment, the converting rate was 9.20 μg/h and K decomposing ratio was 7.83%; spores appeared after 8 h and reached culmination after 32 h; (2) after 15 d composting, the content of total phosphorus(TP) and total potassium(TK) of Mode I increased slightly, the content of available potassium (AK) and available phosphorus (AP) were 97.75% and 19.77% higher than that of CK; (3) the highest fermentation temperature of 2 modes appeared after 5 d and 7 d, and 5℃ and 3℃ higher than that of CK, respectively; (4) the inoculation of K-releasing bacteria had a toxic attenuated effect, especially Mode I; (5) compared with CK, the K-releasing bacteria densities of 2 fermentation products increased by 105.42% and 8.81%, respectively. In total, the inoculation of K-releasing bacteria was beneficial to compost. After weighting evaluation, the evaluation value of 2 modes was 0.57 and 0.29, Mode I was better than Mode II.