Contents of polysaccharides in five species in the family Berberidaceae, including Nandina domestica, Berberis thunbergii, Berberis thunbergii var. atropurpurea, Mahonia fortunei and Mahonia bealei were determined by phenol-sulfuric acid method, and antioxidant activities of polysaccharides in these five species were evaluated by ABTS (2,2’-azino-bis (3-ethyl-benzothiazoline-6-sulfonic acid) diammonium salt) and DPPH (1,1-diphenyl-2-picrylhydrazyl) assays. Average contents of polysaccharides in Nandina domestica, Berberis thunbergii, Berberis thunbergii var. atropurpurea, Mahonia fortunei and Mahonia bealei were 27.82%, 14.52%, 12.14%, 14.44% and 16.80%, respectively. EC50 values of ABTS•+ radical-scavenging capacity were 0.1688, 0.5436, 0.1604, 0.3991 and 0.1689 mg/mL, respectively, and EC50 values of DPPH radical-scavenging capacity were 0.0678, 0.3769, 0.2104, 0.2917 and 0.2224 mg/mL, respectively. There is no significant difference of polysaccharide contents among the same genera, while polysaccharide contents and antioxidant activities are different among various species. Both ABTS•+ and DPPH radical-scavenging capacities were dose dependent, and mathematical model based on dose-effect relationship had high goodness of fit. Contents and antioxidant activities of polysaccharides in Nandina domestica and Mahonia bealei were relatively high, which showed great potential for exploitation and utilization.