An air cushion bed includes an inflatable air mattress a first sensing mat provided on an outer surface of the air mattress and including a first upper and a first lower sensing sheet with a first soft pad sandwiched between them and a first determining module electrically connected to the first upper and lower sensing sheets. When the first sensing mat is compressed and the first upper and lower sensing sheets are electrically connected to each other via holes on the first soft pad, the first determining module determines there is a patient lying on the air mattress or the air mattress with a patient lying thereon is insufficiently inflated. A second sensing mat and a second determining module can be additionally provided on another outer surface of the air mattress opposite to the first sensing mat for the air cushion bed to determine both of the above two situations.
