Abstract: As an indispensable material in the field of electronic packaging, the performance of solder paste directly affects the reliability and packaging quality of the solder joints. Antioxidant, as an important part of solder paste, can prevent the oxidation of active substances in solder paste, and has an important impact on its performance. The effects of ascorbyl palmitate（L-AP）, tert-butylhydroquinone（TBHQ） and sodium diethyldithiocarbamate（DDTC） on the properties of SAC305solder paste were mainly explored by testing the viscosity, collapse performance, spreadability and chromatic aberration of flux and solder paste. Therefore, an effective antioxidant suitable for SAC305 solder paste was screened. The results show that after adding 3wt% antioxidants, the viscosity of flux and solder paste increases, the expansion rate and spreadability all increase. However, the addition of L-AP and DDTC produces some problems, such as blackening of solder joints, bead spatter, thermal collapse and bridge. When TBHQ is chosen as the antioxidant, the viscosity stability of the solder paste is optimum, the expansion rate is biggest, the solder joint morphology and the wetting morphology are plumpest, the collapse resistance is best, the surface chromatic aberration value is small, and the dry phenomenon doesn’t appear, which is suitable for the antioxidant of SAC305 lead-free solder paste.