A medical air mattress, comprising: a lower bedspread; two inclined air cells mounted longitudinally on the lower bedspread, respectively near two sides of the lower bedspread and parallel to each other; a mattress body mounted on the lower bedspread, mounted across the inclined air cells and comprising multiple body air cells and multiple head air cells parallel to each other and arranged in a row to form an air cell row, wherein the head air cells are arranged at a head end in the air cell row; an upper bedspread covering the mattress body, connected securely to the lower bedspread; characterized in the upper bedspread having guardrail sleeves stitched on two-side of the upper bedspread, and the guardrail sleeves are formed adjacent to the edges of two sides of the upper bedspread, each guardrail sleeve having at least one sleeve body; in a guardrail unit mounted in the guardrail sleeves and comprising multiple guardrail air cells mounted respectively in the sleeve bodies of the guardrail sleeve, and in a pumping assembly to control inflating and deflating connected to and selectively inflating the inclined air cells, the body air cells, the head air cells and the guardrail air cells, the pumping assembly comprising: a pump; an inclined pipeline connecting the pump with the inclined air cells; an odd body pipeline connecting the pump with the body air cells and the head air cells at odd rows of the air cell rows; an even body pipeline connecting the pump with the body air cells and the head air cells at even rows of the air cell rows; a guardrail pipeline connecting the pump with the guardrail air cells; and a rapidly releasing valve connected to the odd body pipeline and the even body pipeline, a lower bedspread; two inclined air cells mounted longitudinally on the lower bedspread, respectively near two sides of the lower bedspread and parallel to each other; a mattress body mounted on the lower bedspread, mounted across the inclined air cells and comprising multiple body air cells and multiple head air cells parallel to each other and arranged in a row to form an air cell row, wherein the head air cells are arranged at a head end in the air cell row; an upper bedspread covering the mattress body, connected securely to the lower bedspread; characterized in the upper bedspread having guardrail sleeves stitched on two-side of the upper bedspread, and the guardrail sleeves are formed adjacent to the edges of two sides of the upper bedspread, each guardrail sleeve having at least one sleeve body; in a guardrail unit mounted in the guardrail sleeves and comprising multiple guardrail air cells mounted respectively in the sleeve bodies of the guardrail sleeve, and in a pumping assembly to control inflating and deflating connected to and selectively inflating the inclined air cells, the body air cells, the head air cells and the guardrail air cells, the pumping assembly comprising: a pump; an inclined pipeline connecting the pump with the inclined air cells; an odd body pipeline connecting the pump with the body air cells and the head air cells at odd rows of the air cell rows; an even body pipeline connecting the pump with the body air cells and the head air cells at even rows of the air cell rows; a guardrail pipeline connecting the pump with the guardrail air cells; and a rapidly releasing valve connected to the odd body pipeline and the even body pipeline, a pump; an inclined pipeline connecting the pump with the inclined air cells; an odd body pipeline connecting the pump with the body air cells and the head air cells at odd rows of the air cell rows; an even body pipeline connecting the pump with the body air cells and the head air cells at even rows of the air cell rows; a guardrail pipeline connecting the pump with the guardrail air cells; and a rapidly releasing valve connected to the odd body pipeline and the even body pipeline,