Ultrasonic　Lamb　wave　inspection　is　one　of　nondestructive　testing　approaches,　and　it　has　many　advantages　including　large-area,　omnidirectional,　fast　inspection.　In　common,　narrow-band　frequency　sinusoidal　tone　burst　signal　modulated　by　window　function　is　used　to　excite　guided　waves　in　waveguides　for　mode　control　and　tuning.　For　obtaining　the　signals　at　different　frequencies,　guided　wave　inspection　will　need　to　be　repeated　many　times.　As　an　alternative　of　narrow-band　guided　waves　excitation,　a　broadband　chirp　signal　is　used　for　excitation　signal　and　the　received　signal　is　post-processed　to　obtain　any　one　single　frequency　tone　burst　signal　which　frequency　range　is　located　in　the　frequency　bandwidth.　This　approach　greatly　increases　guided　waves　inspection　efficiency　and　ensures　the　consistencies.　As　the　receivers,　two　PZT　elements　are　supposed　to　be　attached　on　both　sides　of　a　PMMA　plate　in　the　same　location.　The　received　signals　from　two　PZT　elements　are　summed　to　obtain　single　S-0　mode,　and　are　subtracted　to　obtain　single　A(0)　mode　achieving　mode　purification　of　Lamb　waves.　Ultrasonic　Lamb　wave　technology　is　applied　to　inspect　the　plate-like　structures　using　chirp　signal　and　mode　purification.　This　method　is　more　efficient　and　accurate　to　obtain　data　and　much　easier　to　identify,　interpret　and　extract　the　information　of　the　defects.