Clam is one of the important economic shellfish in mariculture in China， with high protein content and complete amino acid species. In this paper， clam was used as experimental material to extract clam protein isolate， and clam protein isolate-dextran conjugates were prepared by wet heat glycosylation reaction. With emulsifying activity and emulsifying stability as the evaluation indexes， the conditions of glycosylation reaction were optimized by single factor combined with response surface method. The result showed that the optimal conditions were 109 ℃， 89 min， pH 11， mass ratio of protein to dextran was 1∶1. Under these conditions， the emulsifying properties and emulsifying stability of glycosylated compound were 1.22 and 75.56， respectively. The results of free amino group content， Fourier transform infrared spectroscopy (FT-IR)， thermal stability， fluorescence spectroscopy and scanning electron microscopy (SEM) showed that the glycosylated product was formed by glycosylation of clam protein isolate and dextran. This study improved the functional properties of clam protein and provided a theoretical basis for expanding the application of clam protein in food industry.