A new heteropolysaccharide was extracted and purified from the fruiting bodies of Cantharellus cibarius Fr. The Cantharellus cibarius Fr. polysaccharide (CC-1) had a molecular weight of 61,056 kDa and was mainly formed of the glucose and xylose at ratio of 5:1. Structure identification of CC-1 was analysed by a combined application of total hydrolysis, high performance liquid chromatography (HPLC), methylation analysis, gas chromatography-mass spectrometry (GC-MS), infrared (IR) spectra and nuclear magnetic resonance (NMR) spectroscopy. The experimental results showed that CC-1 had a backbone of 1,4-linked-β-D-glucose which branched at O-6 and the branches were mainly composed of 6→1)-α-D-xylopyranose residue. CC-1 exhibited significant in vitro antioxidant effect and proliferation effect of immune cells. The activity study showed CC-1 has ability to clear the ABTS+ free radical and DPPH- free radical in a certain range of concentration. The proliferation activity of the immune cells showed that the proliferation effect on B cells was very significant (P<0.001) in the concentration of 0.625-80 mg/ml; and the effect of T cell proliferation was also very significant (P<0.001) in the concentration of 5-20 mg/ml. The result of this study introduced Cantharellus cibarius Fr. as a possible valuable source in exhibiting unique immunoregulatory and antioxidant properties.