This paper makes detailed investigation on a new encapsulation of lon g period fiber grating pair (LPFGP) for liquid refractivity sensing of polymer structures in embeddable form .Polymer material OE4110which has negative thermo-optic coefficient is selected as the base material fo r package.In the package structure,a special groove is introduced,which is convenient for solution to flow through the via. The mounted gratings exhibit lower temperature sensitivity (about 10pm/℃),compared with uncompensated gratings (a bout 120pm/℃).The packaged LPFGP is not sensitive to temperature changes,the package has function of the p rotection and temperature compensation,so it is suitable for liquid refractivity detection.