The invention discloses a Langmuir multi-probe control circuit used for plasma diagnosis and belongs to the technical field of plasma diagnosis. The control circuit is located outside a plasma device and comprises three Langmuir single-probes, an alternating-current sawtooth wave supply voltage generation device, a direct-current supply voltage generation device, a double-pole-double-throw switch, a reversing switch, a first double-pole-three-throw switch, a second double-pole-three-throw switch, a first single-pole-single-throw switch, a second single-pole-single-throw switch and a transform resistor. Selection of the Langmuir single-probes, a double-probe, and a three-probe in different diagnosis circuits is carried out through switching-over of the switches in control circuits, and a cleaning circuit is provided for cleaning of the probes. According to the Langmuir multi-probe control circuit used for the plasma diagnosis, similarities of three probe diagnosis methods on an experimental instrument are used, experimental cost can be saved, different methods can be used by switching-over of the control circuits due to the fact that difference of the three probe diagnosis methods are combined, convenience and high efficiency are achieved, experimental period is greatly shortened, and experimental results are enabled to be accurate due to the fact that the probes can be cleaned during experiment.