Organic/inorganic nano-composite particles are excellent composite materials with high performance in many fields.Fission/fusion process of mini-emulsion polymerization is a novel method to produce this kind of composite material.Based on thermodynamics，basic theory，i.e.minimum interface free energy，was used to derive interface Gibbs free energy equations of equilibrium morphology of organic/inorganic nano-composite particles produced by fission/fusion mini-emulsion process.Several equilibrium morphologies of nano-composite particles i.e.core-shell，hemisphere，sandwich and separate morphologies，were considered.The effect of monomer conversion on nano-composite particles equilibrium morphology was investigated，which expanded the application range of these equations.In carbon/(poly)styrene/water system，core-shell particles had lowest Gibbs free energy when volume ratio of inorganic particles was less than 0.2.With increasing monomer conversion，Gibbs free energy of core-shell，hemisphere and sandwich particles decreased slightly，which could be due to smaller interface tension between polystyrene/water than styrene/water in this system.