The changes of bacteriorhodopsin's structure and function were monitored by the UV/VIS absorption spectrum technique and the flash photolysis technique over the wide pH range (2.1～12.3). The results of the UV/VIS absorption spectra showed that: 1) the wavelength of the characteristic absorption peak was about 568 nm (pH=5.0～10.0), 2) the red shift of the absorption spectra was observed (pH＜5.0) and 3) the blue shift of the absorption spectra was observed (pH＞10.0). The results of the flash-induced kinetics spectra indicated that: a)M₀ (relative concentration of M₄₁₂) kept around 0.038 constantly (pH =7.3～9.5); b) M₀ decreased gradually as pH was below 7.3; c) when pH was above 9.5, M₀ increased obviously and reached the maximum 0.1355 (pH =11.8) then dropped down sharply; d) t^s_1/2 (halftime of the slow component of M₄₁₂) was (4.1±1.1)ms approximately (pH=2.1～7.3) and e) t^s_1/2 was prolonged to 40 677.4ms sharply (pH＞7.3). It can be concluded that under the condition of high pH, the novel pathway and mechanism of bacteriorhodopsin's photocyle may exist.