An adjustable bed includes: a head frame assembly； a foot frame assembly； a knockdown connecting bracket； a slidable assembly having a pair of slidable assembly sides slidable within a pair of lower C steel brackets in a slidable assembly upward direction or a slidable assembly downward direction； a plurality of slidable assembly angle steels； a pair of head lift arm bracket assemblies； a second head tilt angle bracket； a head tilt platform； a head lift platform； a lumbar lift bracket assembly； an upper seat platform； a support platform； a lower seat platform； a head lift motor, secured to the head frame assembly for driving the pair of head lift arm bracket assemblies in a head lift forward direction or a head lift backward direction； and a head support tube, having an upper end pivotally connected to a L bracket and a lower end connected to the head lift platform.
