The invention discloses an LED device for plant light supplementation and a lamp. The LED device for plant light supplementation comprises a base plate, LED wafers, a first adhesive powder layer and asecond adhesive powder layer. The LED wafers are fixed to the base plate through the first adhesive powder layer, and the first adhesive powder layer is a mixture of an adhesive and red phosphor. Thefirst adhesive powder layer is covered with the second adhesive powder layer. According to the LED device for plant light supplementation, through a light formula that composition of the red phosphorand yellow phosphor is motivated by the blue light LED wafers and the ultraviolet LED wafers, full spectrum can be formed and plant photosynthesis characteristics can also be highlighted, when the number of the ultraviolet LED wafers is increased, the components of ultraviolet light in the spectrum are increased, the LED device is especially suitable for cultivation of medicinal plants, a light formula which can be achieved through combination of multiple LED wafers including the red LED wafers, the blue LED wafers, the infrared LED wafers, the ultraviolet LED wafers, the green LED wafers andthe like in the prior art is changed, and the LED wafer invested cost and the circuit and radiator cost are greatly reduced.