A source driver and a driving system for driving an LED panel, and an LED display system are provided. The driving system includes: a plurality of source drivers, for respectively supplying driving currents to channels of different portions on the LED panel, and each source driver includes: a plurality of driving circuits, which are in one-to-one correspondence with the plurality of channels on the LED panel, and are connected to a same current control line, each driving circuit being configured to supply a driving current to a corresponding channel, wherein, the supplied driving current is associated with a voltage on the current control line which the driving circuit is connected with. When one or more driving circuits switch between a non-driving state and a driving state, the driving current being supplied by the driving circuit(s) being in the driving state in the plurality of source drivers is compensated.