The subband energy and lasing wavelength of compressively strained triangular In0.53Ga0.47As/JnAs quantum well are calculated and compared with the conventional rectangular ones with the same strain contents. The strain compensation using Al0.33In0.36Ga0.31 As barrier is introduced. The results show that lasing wavelength can be extended dramatically to beyond 2.8 μm by changing the energy band from the conventional rectangular shape to a triangular one, the realization of such a structure using molecular beam epitaxy technology is also discussed.