In this article, the main emphasis has been given to understand the mechanism of tunability of the optical gain characteristics of W-shaped type-II GaAsSb/InGaAs/InAlAs nano-heterostructure under the variable applied pressure ranging from 1 to 20 GPa along (001), (100) and (110) directions. In pursuance of the calculations, it was examined that the application of inconstant pressure along (001) direction can improve the optical gain insistently with the red shift in wavelength; while the (100) directional pressure reduces the gain with the red shift in wavelength. But, the (110) directional pressure can reduce the gain up to a certain limit of the pressure (similar to 10 GPa), after that it begins to improve the gain characteristics. However, the tuning range of the gain characteristics was restricted in the wavelength limit of similar to 1550-1900 nm. These consequences recommend that such tunable heterostructures can be employed in designing and fabricating the new high power IR-LEDs, bare LED chips, and modern tunable laser gain chips, which can have cantered wavelength at 1550 or 1900 nm.