The present disclosure discloses a lighting device for plant growth, comprising: a lamp, a lifting mechanism, at least two sensing mechanisms and a control mechanism. A light-emitting module is disposed on the bottom surface of the lamp and two ends of the lifting mechanism are coupled to the top surface of the lamp and the control mechanism respectively. Each sensing mechanisms is disposed at the bottom of the lamp. The control mechanism comprises a timing module. When the sensing mechanisms operate that form a signal sensing path and sense a plant to generate a sensing signal, the control mechanism may drive the lifting mechanism according to the sensing signal to control the longitudinal displacement of the lamp. Through the automatic detection and position lifting function, it is possible to provide suitable light sources for plants at different growth stages.