In pharmaceutical industry the major problem of dosage form development is low aqueous solubility. In present review the particle engineering concept and solubility, permeability approaches design and method used in improvement of particle size. The different methods are used in particle engineering like supercritical fluid technology, controlled precipitation, and mechanical technique, evaporation precipitation to aqueous solution, freezing technique, and sonication technology etc. discussed. The improvements of aqueous solubility need to be formulation development for dosage form very essential. The BCS class II drugs modified to soluble form for need of bioavailability of drugs. The solid dispersion method with a different carrier improves the solubility.