A method for washing and purifying ocean engineering engine tail gas by means of seawater with zero energy consumption, comprising: guiding engine tail gas into a washing tower (1) of a washing and purifying system, pumping seawater into the washing tower (1) by means of a seawater pump (2), washing the engine tail gas using the seawater in the washing tower (1), discharging the washing seawater and the washed, purified tail gas out of the washing and purifying system; the washing seawater is subjected to a heat energy recycling step before being discharged out of the washing and purifying system, the heat energy recycling step recovering the waste heat energy of the washing seawater as power energy for the seawater pump (2). Said method recycles and uses the waste heat of the engine tail gas, achieving a high heat recovery efficiency. Also disclosed is a device for washing and purifying ocean engineering engine tail gas by means of seawater with zero energy consumption, which is used for said method, and a s
