The invention discloses a water washing method of a concurrent boiler provided with a boiler water pump, which is used for washing the entrance of an economizer (6) in high flow through an intermittent washing method. The invention has the advantages as follows: the washing time is as short as 1-2 days, which is superior to a washing time of 6-7 days needed in a conventional washing method; and the water consumption is low as follow: a large amount of washing water is saved because the whole washing time is short even through a large amount of water is needed for washing because of the adoption of the intermittent washing method instead of a continuous washing method. The fuel consumption is also reduced because the hot washing time is saved.