【Objective】In order to explore effects of organic material, relative to type, on soil fertility, a 7-year long field experiment was conducted in the desert soil of Hexi Oasis.【Method】The experiment was designed to have 8 treatments, that is, CK (no fertilization), NP (application of chemical fertilizers of nitrogen and phosphorus), NF (70%NP+cow manure), ZF (70%NP+pig manure), JF (70%NP+chicken manure), ZZ (70%NP+biogas sludge), JZ (70%NP+mushroom substrate residue) and WN (70%NP+sewage sludge). All the organic material treatments were the same in organic carbon input and in NP application rate equivalent to 70% of the rate in treatment NP.【Result】Results show that all the organic treatments significantly increased soil organic carbon content and stock as compared with the control (CK) and Treatment NP (P< 0.05), but the increase varied significantly in degree, and was the highest in Treatments JF and WN, which was followed by Treatment ZF and then the rest. The effect on free organic carbon content was significantly higher in Treatments NF, ZF and WN than in Treatments CK and NP, and so was that on soil combined humus content (P<0.05), except in Treatment NF. Moreover, soil loosely combined humus content increased significantly in all the organic treatments, except for Treatment JZ, and so did humic acid (HA) content in all the organic treatments (P<0.05), stably combined humus content in Treatments JZ and ZZ (P< 0.05), tightly combined humus content in Treatments JF, ZZ and WN (P< 0.05), fulvic acid (FA) content in Treatments JF, WN and ZZ (P<0.05), and humin content in Treatments NF and JF only (P< 0.05).【Conclusion】In conclusion, organic materials significantly affects free soil organic carbon and combined organic carbon in content and combination form and composition of humus, an hence soil organic carbon content and stock, and the effects of pig manure, chicken manure and sewage sludge improving soil fertility are higher than those of cow manure, mushroom substrate residue and biogas residue.