The divergent far-field distribution of III-nitride ultrathin film-transferred light-emitting diodes (FTLEDs) with ellipse holes of triangular photonic crystal (PhC) lattice have been experimental and theoretical studies. Angular-and-spectral-resolved measurement revealed guided modes extraction behaviors which obtain good agreement with theoretical model according to two-dimensional free photon band structure. The azimuthal evolution of the guided modes' diffraction behavior according to Bragg's diffraction has also been discussed by angular-resolved monochromatical mapping. Finally, the PhC FTLEDs show light enhancement with the divergence far-field pattern that exhibited 130% at a driving current of 200mA as compared with non-PhC (without PhC) FTLEDs. This could lead to promising LEDs with unusual divergent far-field properties for specific applications.