The invention discloses a water-based adhesive for electrostatic flocking of a cold-rolled coated steel sheet for oceanographic engineering. The water-based adhesive is characterized by comprising the following components in parts by weight: 100 parts of acrylic acid modified polyurethane emulsion, 4-22 parts of carbon black, 0.03-1.3 parts of organosiloxane, 0.007-0.07 part of an isothiazolinone bactericide, 0.04-1 part of sodium alkyl benzene sulfonate, 0.2-1 part of carboxymethyl cellulose sodium and 3-10 parts of water-based tackifying resin. The adhesive for the electrostatic flocking of the cold-rolled coated steel sheet is prepared by the following steps: adding the acrylic acid modified polyurethane emulsion and the carbon black into a mixing reaction kettle, stirring and simultaneously adding the organosiloxane, the isothiazolinone bactericide, the sodium alkyl benzene sulfonate and the carboxymethyl cellulose sodium, continuing to stir, reducing the stirring speed, and adding the water-based tackifying resin to obtain the adhesive for the electrostatic flocking of the cold-rolled coated steel sheet. The adhesive disclosed by the invention is long in storage life, high in adhesive strength, good in waterproofness, good in flexibility, good in corrosion resistance, good in oxidation resistance and stable in long-term usability.