Jicama　is　a　widely　cultivated　but　unexploited　crop.　This　study　isolated　and　characterized　polysaccharide　from　roots　of　Pachyrhizus　erosus　(PEP).　Optimal　extraction　conditions　were　obtained　using　single-factor　experiment　and　response　surface　methodology,　after　which　an　extraction　rate　of　41.55%　was　obtained.　Contents　of　total　sugar,　uronic　acid,　moisture,　and　ash　were　about　85.24%,　10.82%,　1.55%,　and　0.05%,　respectively.　PEP　had　relative　molecular　mass　of　18.3　kDa　and　tangled　filaments　and　loose　flaky　structure.　PEP　was　thermostable　and　presented　high　oil　holding　capacity　but　relatively　low　emulsion　properties.　Rheological　tests　indicated　that　the　viscosity　of　PEP　was　of　concentration　and　temperature　dependence.　Salt　additions　at　various　concentrations　caused　only　slight　increase　of　viscosity　and　storage　modulus.　In　a　word,　PEP　from　jicama　was　a　type　of　acidic　polysaccharide　with　high　thermostability　and　oil　holding　capacity.　However,　emulsion　properties　and　viscosity　are　relatively　low.　Fine　chemical　structure　and　bio-function　of　PEP　need　further　investigations.