At present, offshore separate-layer sand control and separate-layer water injection face short validity, long construction period and high operation cost. To solve these problems, this paper researched a new efficient integration technology of separate-layer sand control and separate-layer water injection for offshore oilfields. Crossing-type suspension release packer can connect sand control pipe string and water injection pipe string simultaneously, and small-diameter hydraulic compression four-rubber separate-layer packer can realize the setting of separate-layer sand control packer and the later fine stratification of water injection pipe string. By virtue of this technology, sand control pipe string and water injection pipe string are run into the hole in one trip, which saves the construction time more than 50%. After the soluble release support sleeve of crossing-type suspension packer is dissolved, sand control pipe string and water injection pipe string can be maintained independently, which extends the service life of sand control pipe string and reduce the operation cost. This technology has been successfully applied 10 well times in Shengli offshore oilfield with maximum hole deviation angle 65 °, maximum tool setting depth 3 780 m, maximum working pressure difference 10 MPa, construction success ratio 100% and stratification qualification rate 100%, and it effectively improves the development degree of offshore water flooding oil reservoirs.