Disclosed is a Zn-Ni based composite plated steel sheet excellent in corrosion resistance and workability which comprises a ferrous substrate and, provided thereon, a Zn-Ni based composite electroplating layer comprising 1-15% by weight of Ni, 0.1-10% by weight of Cr, 0.1-10% by weight of SiO.sub.2, 0.01-3% by weight of Fe and the balance being essentially Zn. This steel sheet may further have a Zn or Zn based alloy electroplating upper layer to further improve corrosion resistance after coating. Furthermore, in order to remarkably improve corrosion resistance, the steel sheet may further have a hardly soluble chromate film layer of 10-150 mg/m.sup.2 in total Cr content and an epoxy resin thin film layer containing agglomerated SiO.sub.2 provided on said chromate film layer.This is a continuation-in-part of pending U.S. patent application Ser. No. 07/272,846 filed Nov. 18, 1988 and entitled "Zn--Ni BASED COMPOSITE ELECTROPLATED STEEL SHEET", disclosure of which is incorporated herein be reference.