The　water　absorption　and　desorption　process,　the　interfacial　transition　zone　(ITZ)　and　the　cracking　behaviour　of　lightweight　aggregate　concrete　(LWAC)　were　obtained　by　a　U-tube　micro-pressure　measurement　device,　a　scanning　electron　microscopy　test　and　a　new　restrained-shrinkage　ring　device,　respectively.　The　study　reveals　that,　with　the　increase　in　degree　of　ceramsite　prewetting,　the　water　absorption　ability　declines,　while　the　water　desorption　ability　improves　for　ceramsites　embedded　in　the　LWAC,　and　the　ITZ　of　the　LWAC　becomes　compact.　The　cracking　ages　of　the　LWAC　rings　with　ceramsites　prewetted　for　0　h,　1　h　and　24　h　are　respectively　10.7　days,　15.3　days　and　25　days.　At　the　age　of　28　days,　the　crack　width　of　LWAC　rings　decreases　with　the　increase　in　degree　of　ceramsite　prewetting.　Also,　with　the　increase　in　degree　of　ceramsite　prewetting,　the　restrained-shrinkage　cracking　behaviour　of　the　LWAC　rings　improves.　The　research　results　provide　clues　for　the　preparation　of　the　LWAC　with　better　crack-resistant　behaviour.