Several etching methods for mesa of InAs/GaSb superlattice in IR FPA were investigated. The InAs/GaSb superlattices used here were prepared by molecular beam epitaxy. A standard PIN device structure was applied in all samples with a period of 8ML InAs/8ML GaSb. Inductively coupled plasma etching with CH4, Cl2 and Ar as reactive gases and wet etching with solution including orthophosphoric acid and tartaric acid were compared. The mesa height was measured by α-step meter system, while surface morphology was evaluated by microscope and scanning electron microscopy. The results shows that CH4 based etching can give a smooth surface and slippery lateral with an 80 degree angle. Furthermore, the mesa depth was easy to control. This method is suitable for fabricating deep mesa device. It has also been found that etching with the solution based on orthophosphoric acid can obtain a smoother, clear surface and low in the longitudinal. It is a better way to fabricate IR FPA.