The present invention is directed to an amorphous form, three novel polymorph form of crystalline varenicline tartrate, namely Form D, Form E and Form F. The present invention also provides processes of their preparations and pharmaceutical composition comprising such material and their use in therapy. Form D is new anhydrous varenicline tartrate, and can be prepared from recrystallizing varenicline tartrate in a mixture of methanol and water or a mixture of N,N-dimethylformamide and water. Form E is a new varenicline tartrate monohydrate, and can be prepared recrystallizing varenicline tartrate in a mixture of isopropanol and water. Form F is another new varenicline tartrate monohydrate, and can be prepared recrystallizing varenicline tartrate in a mixture of acetone and water. The X-ray powder diffraction pattern (X-RPD), Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques are used to characterize amorphous form and crystalline polymorphic forms.