Abstract: A method is proposed for the monitoring of a plant having a plurality of sub-systems which is operable at variable working points. Respective measured values are detected for a fixed set of process parameters (B, U, S1, . . . , SN) at pre-settable time intervals during the operation of the plant (1). The measured values detected in a learning phase for different working points are used to prepare models (M1, M2, . . . , MN) for the operating characteristics of the sub-systems (11, 12, . . . , 1N). At least one monitoring parameter (Ri, Rik), which is independent of the respective current working point, is determined at pre-settable time intervals in an operating phase using the models (M1, M2, . . . , MN) and the time-dependent course of the monitoring parameter (Ri, Rik) is used for the monitoring of the plant (1).