The invention relates to a natural cold source cooling water chiller which comprises an outdoor unit and an indoor unit, wherein the outdoor unit mainly consists of a refrigeration system composed of a totally-enclosed scroll compressor, an evaporator, an evaporative condenser and a natural cold source collection device, and a water channel circulating system with a three-way valve so as to realize the mechanical refrigeration of the evaporative condenser and the evaporative cooling and the air cooling of the natural cold source collection device. The water chiller is characterized in that the evaporative condenser and the high-efficiency natural cold source collection device are arranged simultaneously above a cooling circulating water pool, and an axial-flow fan is installed on upper space. When the outdoor wet-bulb temperature is higher than 6 DEG C to 8 DEG C, the evaporative condenser is mainly used to realize refrigeration, when the outdoor wet-bulb temperature is lower than 6 DEG C to 8 DEG C and higher than 0 DEG C and 2 DEG C, the natural cold source collection device which is in the form of cooling tower spraying is mainly used to realize the evaporative cooling, and when the outdoor wet-bulb temperature is lower than 0 DEG Cto 2 DEG C, the natural cold source collection device which is in the form of air cooling is mainly used to realize cooling.