The invention provides vacuum drying equipment and a monitoring device, and relates to the technical field of film forming processes. The monitoring device is used for monitoring a printing layer andcomprises a monitoring probe, a control assembly and a driving mechanism, wherein the monitoring probe is arranged opposite to the printing layer and comprises a light path system, a light source andan induction assembly, the light source is provided with a light outlet hole facing the light path system, the induction assembly is provided with a light inlet hole facing the light path system, thelight path system is used for forming a conjugate image of the light outlet hole in the side, which is close to the printing layer, of the light path system, and the light inlet hole is conjugated with the conjugate image; and the induction assembly is used for outputting an induction signal according to the light entering the light inlet hole. The control assembly is used for outputting a controlsignal until the intensity of the induction signal reaches a threshold value. The driving mechanism is connected with the monitoring probe and used for driving the monitoring probe to move towards the printing layer in response to the control signal. The monitoring device can monitor the change of the liquid level of the printing layer and provide data for adjusting the vacuum drying equipment.