Using the high resolution Fourier transform spectrometer the B²S⁺-X²S⁺ band system of AlO molecule has been recorded. The rotational structure of eighteen bands belonging to B²S⁺-X²S⁺ transition of AlO have been analyzed which led to accurate rotational and vibrational constants of ground and excited states. A few bands, viz. (2, 1), (3, 2), (4, 3), (2, 3), (3, 4), (4, 5), and (5, 6) were analyzed for the first time. Using these constants, the Franck-Condon factors and r-centroids were computed for the bands of B-X, C-X and C-A band systems for the n¢ = 0-8.; n¢¢ = 0-8 matrix using the method developed by Jarmain and Nicholls. The F-C factors and r-centroids obey the established relationships.