For any finite group G,  its module category Rep(G) is a symmetric braided fusion category.  The modular extensions of  Rep(G) have been studied extensively by Muger, Drinfeld-Gelaki-Nikshych-Ostrik, Lan-Kong-Wen and others. In this talk we will present a connection between modular extensions and orbifold theory, and discuss how  this connection leads to a proof of a conjecture by Dijkgraaf-Pasquier-Roche on holomorphic orbifold theory.