In this study, we have investigated the antiviral activity of GuiQi polysaccharides (GQP) upon enterovirus 71 (EV71) in vitro. An assay using methyl thiazolyl tetrazolium (MTT), and analyses of cytopathic effects (CPE) were used to examine the antiviral activity of GQP upon Vero cells infected with EV71. The results revealed that GQP at concentrations below 31.2 μg/mL exhibited significant antiviral effects upon EV71 when applied under three different experimental protocols. GQP was most strongly active in preventing the adsorption of EV71 to target cells and in this respect it was significantly more effective than ribavirin. In addition, it was clear that GQP could inhibit viral replication when added to cells 2 h after infection, but if added at the point of infection its effect was weak. GQP is considered to be less toxic than ribavirin, and may warrant further evaluation as a possible agent in the treatment of hand, foot and mouth disease (HFMD).