Abstract: Addressing the problems of low automation level of the manual random checking of the steel plate pre-bending edge morphology quality data and insufficient inspection points, an on-line inspection system is designed with the lazar measurement technique. Elaborated here in the article are the principle for inspection of the pre-bending morphology and the application effect of the automatic on-line inspection system. The said system is capable of automatically measuring the chord height and the straight length of the pre-bending edge by means of simulating the manual measurement of the chord height and the straight length. The comparison between the automatic measurement data and the manual measurement data shows that both the measurement accuracy and efficiency of the above mentioned automatic inspection system meets the applicable requirements.