Nifedipine is poorly soluble in water and has low bioavailability.Microemulsionwhich is the ideal carrier of difficult soluble drugscan increase the solubility of drugs.The study prepares nifedipine into microemulsion typeand thus its solubility is increased and its bioavailability is improved to a certain extent.The formulation of nifedipine microemulsion is optimized via the pseudo-ternary phase diagram and the amount of nifedipine dissolved in different surface active agentssurfactants and oil phases.The optimized nifedipine microemulsion formulation consists of emulsifier OPanhydrous ethanolethyl oleate and water with the weight ratio of 27∶13.5∶4.5∶55.The prepared microemulsion is light yellowcleartransparent and has good mobility.When the microemulsion is diluted by waterits shape is spherical under transmission electron microscopy with an average diameter of 22.89 nm.It shows good stability after high speed centrifuging and reserved sampleand also their content and diameter have no obvious change.The nifedipine microemulsion is easy to prepare by this methodand its solubility is improved more than 700 times.