The invention discloses an offshore oilfield double-pipe water injection pipe column and method. In the offshore oilfield double-pipe water injection pipe column, an inner pipe column body comprises an inner pipe and a polished rod which are connected in the up-down direction; an outer pipe column body comprises an outer pipe; a constant-pressure screen pipe, a double-stage inner sealing tool anda well-washable sealing tool are further arranged on the outer pipe; the constant-pressure screen pipe is located below a crossing-type annulus safe packer and communicates with an annulus between theinner pipe and the outer pipe and an upper oil layer; the double-stage inner sealing tool is located below the constant-pressure screen pipe, is matched with the polished rod for sealing and blocks the annulus between the inner pipe and the outer pipe; the well-washable sealing tool is located at the lower end of the outer pipe and is matched with a sand prevention sleeve sealing cylinder for sealing, wherein the sand prevention sleeve sealing cylinder is arranged between sand prevention sleeves located in the upper oil layer and a lower oil layer; and the lower end of the polished rod communicates to the lower oil layer. According to the offshore oilfield double-pipe water injection pipe column, the construction steps can be simplified, the layering effect is improved, the service life is prolonged, and the high environmental protection and safety requirement of offshore oilfield development is met.