Cordyceps militaris is an edible and medicinal fungus that has been traditionally used as a crude drug for treatment of human disease. Meanwhile, the functional nutrient substances in C. militaris possess various physiological activities. In addition, re-utilizing the soybean curd residue as solid medium for producing edible and medicinal fungus is an efficient and commercial method to dispose of the soybean curd residue waste materials. In this study, soybean curd residue was utilized as solid medium raw material for fermentation by C. militaris mycelium. The crude polysaccharide (CSCPS) from fermented soybean curd residue and C. militaris mycelium mixture showed potent bioactivities, including antioxidant, antitumor and immunomodulatory activities. Based on five antioxidant assays, the CSCPS showed powerful antioxidant capacities at OH, DPPH and ABTS radical scavenging assays. The CSCPS significantly activated the proliferation of RAW 264.7, and protected it from DOX-induced and LPS-stimulated cell damage. Furthermore, the CSCPS inhibited the proliferation of HT1080, Hela, A549, U-2 OS and MDA-MB-231 cells.