Abstract: Aiming at the problems of high cost and long time of tank opening inspection for in-service storage tanks, a Lamb wave full focus imaging inspection method is proposed to realize the corrosion inspection of the bottom plate of metal storage tanks without tank opening. Firstly, the Lamb wave propagation mode is simulated by simulation software, and the Lamb wave detection mode used for tank floor detection is determined according to the simulation results. Secondly, the research on Lamb wave full matrix data acquisition and imaging algorithm is carried out, the Lamb wave full focus imaging algorithm suitable for tank bottom plate detection is established, and the Lamb wave detection software system for tank bottom plate is developed. Finally, the simulated defect sample of tank bottom plate is tested and verified, and the results show that the imaging algorithm detection results are effective and reliable.