In order to reveal the best ratio of rice straw and pig manure instatic aerobic co-composting，the indoor culture methodwasadopted，and the humus composition was used as the basis forevaluation.Seven mass ratios of rice straw to pig manure[10∶0(Rs)，9∶1(Rp1)，7∶3(Rp2)，5∶5(Rp3)，3∶7(Rp4)，1∶9(Rp5)and 0∶10(Pm)]were designed and their C contents of water-soluble substance，humic -extractable acid，humicacid humin(C WSS，CHE，CHA and CHu)，E 4/E6 ratio ofhumic acidalkali extract and humificationindex(C HA/CFA)were analyzed.The results showedthat:(1)Compared with ricestraw，pig manure contained higher levels of C WSS and CHA，while C Hucontent waslower；(2)Compared with 0d，the content of CWSS and CHudecreased at different levels at the end ofcompost.Amongthem，the Rp1 treatment had the greatest consumption of CWSS，and the Rp3 treatment had the strongest decomposition of C Hu；(3)In the testedtreatments，only Rp1 treatment increased CHEby 13.1% at the end of composting，and C HEof the other treatments were all consumed；(4)Rp5 treatment promotedthe condensation of HA molecules at the end ofcomposting，on thecontrary，the degree of aromatization of HA molecules fromthe other treatmentsdecreased.With thecomposting，the HA of each treatment showed the first degradation andrecondensation.The rice straw accounted for ≥ 30% of the total mass ofcompost，which was beneficial to the improvement of humus qualityafter composting，while the pig manure accounted for ≥ 90% of the total mass of compost，the humus quality decreased after composting.