The optimal culture conditions of exopolysaccharides (EPS) production in submerged culture medium by Stropharia rugosoannulata 2# were determined using the orthogonal matrix method. The optimal defined medium (per liter) was 60.0 g sucrose, 6.0 g tryptone, 5 mM KH₂PO₄, and initial pH 7.0 at 28°C. In the optimal culture medium, the maximum EPS production was 9.967 g/L in shake-flask culture. One fraction of EPS was purified from the culture filtrates by size exclusion chromatography (SEC), and the molecular characteristics were examined by a multiangle laser-light scattering (MALLS) and refractive index (RI) detector system. The weight-average molar masses and the polydispersity ratio of the EPS fraction were determined to be 5.305 × 103 g/mol and 2.014, respectively. FTIR spectroscopy was used for obtaining vibrational spectra of the purified EPS fraction. The obvious characteristic absorption at 884.3 cm-1 revealed the existence of β configuration. Furthermore, the experiments in vitro indicated that S. rugosoannulata 2# EPS exhibit high antitumor and antioxidative effects.