As an important parameter, Reduction capacity (RC) is recognized for evaluating redox characteristics of humic acids (HA) in environment. In this study, three HAs (tagged as SH, TJ and JY respectively) from different sources were selected and pretreated through methods of saturated hydrogen oscillation and soil solution incubation respectively for determining chemical reduction capacity (CRC) and microbial reduction capacity (MRC) by reduction of two electron acceptors including ferric nitrate (Fe(NO₃)₃) and ferric citrate(FeCit), in comparison with native reducing capacity (NRC) obtained through the same measurement method based on HA samples without any pretreatments. The results suggested that HA extracted from local humus layer of soil in JinYun Mountain had the greatest RC among three humic acids, which showed the highest RC values of 20.21±0.26 mmol_cmol^-1C(NRC), 26.02±1.12 mmol_cmol^-1C(CRC) and 29.29±1.56 mmol_c mol^-1C(MRC), respectively. Meanwhile, Of the two electron acceptors, Fe(NO₃)₃ induced much higher RC than FeCit. In addition, HA in solution status showed higher RC than in solid status. All the above findings demonstrate that reduction capacity (RC) of HA is a variable parameter, which is closely related to the structure and properties of the HA per se and also affected by its initial status (e.g. solution or solid) and electron acceptors. Comparison between the RC indexes of the HAs shows that CRC and MRC were evidently higher than NRC, however no significant difference in magnitude was observed between CRC and MRC. However, whether it is feasible to use CRC to characterize MRC needs further study for validation.