Due　to　its　significance　in　mathematics　and　engineering,　the　operator　theory　of　Krein　spaces　and　Krein　space　approaches　have　been　being　attracted　attention　of　many　mathematicians.　Recently,　the　concept　of　frame　has　been　introduced　in　Krein　spaces.　This　paper　addresses　the　approximate　oblique　dual　frames　for　Krein　spaces.　We　present　some　parametric　expressions　and　constructions　of　approximate　oblique　dual　frames　of　a　given　frame　sequence　and　prove　that　there　exists　a　bijection　between　the　approximate　oblique　dual　frames　of　a　given　frame　sequence　and　its　portrait　under　a　bounded　invertible　operator　on　&　ell;2$$　{\ell}＜^＞2　$$　and　between　the　approximate　oblique　dual　frames　of　original　and　perturbed　frame　sequences.　Also,　we　estimate　the　deviation　of　the　canonical　approximate　oblique　dual　frames　of　original　and　perturbed　frame　sequences　and　give　an　explicit　characterization　for　the　best　approximation　of　the　approximate　oblique　dual　frame　of　original　frame　sequence　using　that　of　perturbed　frame　sequence.　Finally,　applying　our　results　to　shift-invariant　systems,　we　derive　some　new　results　in　shift-invariant　spaces.