Atorvastatin calcium is an anti-hyperlipidemic drug that competitively inhibit HMG-CoA reductase and decrease production of cholesterol in liver. This statin derivative is highly metabolized in gut wall and liver so that it produces only 14% oral bioavailability. In this study we aim to improve the bioavailability of BCS II drug atorvastatin calcium in the formulation of mouth dissolving tablet, which enters the blood stream via facial, jugular artery and vein, by penetrating the lipid membrane when the tablet disintegrates. The Atorvastatin – chitosan nanoparticles was formulated by freeze drying of colloidal solution of nanoparticles. Super disintegrant like croscarmellose sodium, crospovidone, and sodium starch glycolate were added and tested for its dispersion properties. The prepared formulation shows enhanced rate of dissolution and may helpful by avoiding first pass metabolism and to achieve maximum bioavailability. Further the polymeric nano formulation (atorvastatin-chitosan nano particle) allows drug to penetrate much faster and dissolve the drug in saliva. Finally, the prepared formulation is evaluated by pre formulation studies, pre compression evaluation, post compression evaluation and the result of the study revealed that atorvastatin chitosan nanoparticles with size of 406 nm and PDI 0.246 had 118% dissolute in 10 min and shows enhance bioavailability.