β-1,3-Glucan binding protein (β-GBP) was purified from the haemolymph of Episesarma tetragonum by affinity chromatography with epoxy-activated laminarin-sepharose CL-6B column. E. tetragonum β-GBP exhibits a single band with a molecular weight of 100kDa on SDS-PAGE and a pI of 5.9 in isoelectric focusing (IEF). The circular dichroism (CD) spectra result of E. tetragonum β-GBP indicates that the negative ellipticity bands near 220nm and 208nm correspond to the β-sheets in the secondary structure. Functional analysis results demonstrate that the purified E. tetragonum β-GBP agglutinates fungal cells (Candida albicans) containing β-glucan. This recognition and binding specificity leads to the activation of the prophenoloxidase (ProPO) cascade and enhance the phenoloxidase (PO) activity in a dose-dependent manner. Our finding discloses new insights in the ProPO activation and fungal agglutination of purified E. tetragonum β-GBP. It seems to play a significant role in microbial uncovering mechanism in invertebrates.