With potential anti-tumor and antioxidant properties, the polysaccharide content ofD. nobileis relatively lower than that of the other medicinalDendrobium.To find high-content polysaccharide resources, the polysaccharide (DHPP-Ⅰs) was prepared fromD.Second Love ‘Tokimeki’ (aD. nobilehybrid) and compared with DNPP-Ⅰs fromD. nobile. DHPP-Is (Mn 31.09 kDa) and DNPP-Is (Mn 46.65 kDa) were found to beO-acetylated glucomannans (-Glcp-(1,4) andO-acetylated-D-Manp-(1,4) backbones), analogous to otherDendrobiumpolysaccharides. DHPP-Ⅰs had higher glucose content (31.1%) and a lower degree (0.16) of acetylation than DNPP-Ⅰs (15.8%, 0.28). Meanwhile, DHPP-Ⅰs and DNPP-Ⅰs had the same ability in the radical scavenging assay, which was milder than the control of Vc. Both DHPP-Is and DNPP-Is inhibitedSPC-A-1cell proliferation in vitro, with obvious differences in dose concentrations (0.5–2.0 mg/mL) and treatment times (24–72 h). Therefore, the antioxidant activity of DHPP-Ⅰs and DNPP-Ⅰs is not associated with distinction in anti-proliferative activity. As a glucomannan derived from non-medicinalDendrobium, DHPP-Ⅰs has similar bioactivity to other medicinalDendrobium,and this could serve as a starting point for studying the conformational–bioactivity relationship ofDendrobiumpolysaccharides.