In the case of effective mass and dipole approximation, considering the built-in electric field(BEF) generated by spontaneous and piezoelectric polarization, strain caused by lattice mismatch and adjustment of material parameters by static pressure of external fluid, the effects of BEF and external hydrostatic pressure on the absorption coefficient of exciton optical transition and linear optical refractive index variation in a strained wurtzite(WZ) GaN/AlxGa1－xN cylindrical quantum dot are investigated by using variation method and density matrix method. Results show that the absorption peak intensity of exciton optical transition and linear optical refractive index are reduced by built-in electric field. The absorption peak of optical transition and two peaks of linear optical refractive index move towards low energy direction, and red-shift occurs obviously. The higher the content of Al in ternary mixed crystal, the greater the red-shift amount will be. Absorption peak intensity of exciton light transition and variation range of linear optical refractive index are reduced by hydrostatic pressure. The absorption peak of optical transition and two peaks of linear optical refractive index move towards high energy direction, and blue-shift occurs.