A direct expansion evaporator for making a frozen product from raw material includes a feeding channel, a heat exchange channel thermally communicating with the feeding channel, and a refrigerant flowing within the heat exchange channel for exchanging heat between the raw material within the feeding channel and the refrigerant within the heat exchange channel in an expanded evaporation manner. Therefore, the refrigerant releases the thermal energy via the phase changing from liquid to gaseous state of the refrigerant. The heat exchange channel has a pre-cooling portion for pre-cooling the raw material at a predetermined temperature and a freezing portion for freezing the raw material to a final predetermined temperature of the frozen product in two-stage evaporation manner. Thus, the direction expansion evaporator provides a relatively more efficient way for making the frozen product, so as to increase the quality of the frozen product.