Rice false smut is a world-wide fungal disease caused by Ustilaginoidea virens. In this study, we found an ester cyclase, UvEC1, was significantly up-regulated during U. virens infection. UvEC1 contained a ketone cyclase Snoal-like polyketide cyclase domain and the functions of this important class of proteins in plant fungal pathogens remain unclear. Deletion of UvEC1 caused defects in vegetative growth and conidiation. UvEC1 is also required for response to hyperosmotic and oxidative stresses, and maintenance of cell wall integrity. Importantly, the ∆UvEC1 mutants exhibited reduced virulence. We performed an TMT-based quantitative proteomic analysis to identify differentially expressed proteins (DEPs) between ∆UvEC1-1 mutant and the wild type HWD-2. Proteomic data have revealed that UvEC1 have various effects on metabolism process, localization, catalytic activity, binding and spliceosome. Taken together, our findings suggest that UvEC1 is critical for development and virulence of U. virens.