The invention relates to the field of oil and gas exploitation, in particular to a flow pattern regulator and a large temperature difference constant rheological oil-based drilling fluid. The flow pattern regulator contains a component A, a component B, a component C and a component D. The component A is a first copolymer containing a structural unit provided by dimer fatty acid, a structural unitprovided by a diamine compound and a structural unit provided by fatty amine polyoxyethylene ether; the component B is a second copolymer containing a structural unit provided by long chain dibasic acid, a structural unit provided by a diamine compound and a structural unit provided by a diol compound; the component C is a third copolymer containing a structural unit provided by dimer fatty acidand a structural unit provided by fatty amine polyoxyethylene ether; and the component D is an ether compound. The large temperature difference constant rheological oil-based drilling fluid containingthe flow pattern regulator provided by the invention can maintain the dynamic shear force meeting the safe drilling requirements of deepwater drilling at the present stage within the temperature of 2-120DEG C.