The invention discloses a height-adjustable metal nursing bed which comprises a mattress rack and two supporting mechanisms, wherein each of the supporting mechanisms comprises a supporting assembly,a trundle assembly and a telescopic assembly; the trundle assembly comprises two parallel fixed panels which are aligned to each other; each of the supporting mechanism comprises two symmetrical supporting legs, and each supporting leg comprises a limiting supporting rod and a connecting supporting rod; the limiting supporting rods and the connecting supporting rods are parallel to each other; oneends of the limiting supporting rods and the connecting supporting rods are hinged to the side beams of the mattress rack while the other ends are hinged to the fixed panels; a connecting cross rod is arranged between the two connecting supporting rods of the two supporting legs; a limiting bump is formed in the limiting cross rod; and the telescopic assembly comprises an electric telescopic rodand the electric telescopic rod is located on the axle wire of a bed body.