We report the thickness effect of amorphous silicon for the polycrystalline silicon (poly-Si) layer laterally crystallized by blue laser annealing (BLA) using 50 mu s melting time. The grain size is much larger and full width at half-maximum of Raman intensity is lower compared to those of the poly-Si by excimer laser annealing. It is found that the average width of lateral grain is wider than 3 mu m and full width of half maximum of Raman intensity for the BLA poly-Si with an optimum thickness of 90 nm is 3.32 cm(-1). The p-type poly-Si thin-film transistor with 90 nm exhibits field-effect mobility of 161.91 +/- 6.14 cm(2)/Vs and subthreshold swing of 227 +/- 7 mV/dec.