The invention relates to an energy-saving street lamp based on the Internet of things and having a light supplement function. The energy-saving street lamp comprises an illuminating lamp and a lamp post, and further comprises a light supplement mechanism and an adjusting mechanism. The light supplement mechanism comprises a steering assembly, a first fixing rod, a second fixing rod, a first air cylinder, a lifting rod, two transmission rods, two rotating plates and two reflective mirrors. The adjusting mechanism comprises a drive assembly, a moving assembly, an outer shell, a moving rod, a drive frame, a connecting rod, a solar pane and a limit block. The steering assembly comprises a third fixing rod, a first sleeve, a first gear, a second gear and a first motor. In the energy-saving street lamp based on the Internet of things and having the light supplement function, when the street lamp breaks down, light supplement can be conducted on the radiation range of fault street lamp by adjusting the radiation angle of an adjacent street lamp through the light supplement mechanism, and thus the driving safety is improved; and through the adjusting mechanism, the position and angle of the solar panel are adjusted, and the generating efficiency of the solar panel is improved.