The present invention relates to a water purification system having a sterilization device and a sterilization method using the same, which are capable of sterilizing overall purified water contained in a water storage tank. According to the present invention, provided is the water purification system having a sterilization device, the water purification system comprising: a filter unit which includes one or more filters configured to filter raw water supplied from the outside a water storage tank which has an inlet configured to receive purified water filtered by the filter unit and an outlet configured to discharge the purified water, and which is configured to store the purified water and a sterilization device which is connected to the filter unit, and which sterilizes the purified water while circulating part of the purified water having passed through the filter unit wherein the sterilization device comprises: an ultraviolet ray light-emitting diode (UV LED) which is disposed on the upper side of the inside of the water storage tank, and which sterilizes the stored purified water a circulation conduit which is disposed outside the water storage tank, and which communicates with the inlet and the outlet to thus form the circulation path of the purified water stored in the water storage tank and a circulation pump which is disposed to connect to the circulation conduit at the lower end of the water storage tank, and which circulates part of the stored purified water by providing power to the circulation path.COPYRIGHT KIPO 2017본 발명은, 외부로부터 공급되는 원수를 필터링하는 하나 이상의 필터를 포함하는 필터부, 상기 필터부에 의해 필터링 된 정수를 유입시키는 유입구 및 상기 정수를 유출시키는 유출구를 구비하고, 상기 정수를 저장하도록 이루어지는 저수조, 및 상기 필터부에 연결되고, 상기 필터부를 통과한 정수의 일부를 순환시키면서 살균 가능하게 하는 살균장치를 포함하고, 상기 살균장치는, 상기 저수조 내부의 상측에 설치되어, 상기 저장된 정수를 살균하도록 이루어지는 UV LED(Ultraviolet Ray Light Emitting Diode), 상기 저수조의 외부에 설치되고, 상기 저수조에 저장된 정수의 순환유로를 형성하도록 상기 유입구 및 유출구에 연통되는 순환배관, 및 상기 저수조의 하단에서 상기 순환배관에 연결되도록 배치되고, 상기 순환유로에 동력을 제공하여 상기 저장된 정수의 일부를 순환시키는 순
