Experimentations reveal that antifreeze proteins (AFPs) in solution can bind on ice surface and shape the ice crystals. Based on the theory of ice crystal growth, the shape of an ice crystal is determined by its most slowly growing faces. If the driven force of phase transformation is given, the growth rate of each face is determined by the configuration of ice-liquid interface. The effects of bound AFPs on equilibrium configuration of ice-liquid interface have been obtained by using the theory of polymer chemistry. The results suggest that sharp rough ice-liquid interfaces of binding AFPs translate into sharp singular interfaces.