An anomaly detection method for a process instrument, comprising: receiving by a programmable logic controller PLC measurement data of a process instrument, wherein the measurement data is periodically stored in a historical database, and wherein at least one virtual function module is integrated on the programmable logic controller PLC, wherein a mapping is set between at least one input channel of each virtual function module and an output of at least one anomaly diagnosis algorithm arranged on a service provision system, each anomaly diagnosis algorithm being used to diagnose whether an anomaly exists in a process instrument; upon receiving, via an input channel of the virtual function module, an anomaly indication outputted by the service provision system, the programmable logic controller PLC determines that an anomaly exists in the process instrument corresponding to the anomaly diagnosis algorithm, wherein the anomaly indication is an indication outputted when the service provision system determines that an anomaly has occurred in the process instrument after acquiring the measurement data from the historical database and using the corresponding anomaly diagnosis algorithm to diagnose the measurement data, wherein each anomaly diagnosis algorithm is disguised as an algorithm module of the PLC, such that the anomaly indication is outputted to a corresponding input channel of the PLC and the anomaly indication participates in PLC control directly as an input parameter of the PLC; and wherein the programmable logic controller PLC controls a process execution mechanism according to the measurement data when the anomaly indication is not received, and controls the process execution mechanism according to a preset default datum when the anomaly indication is received. receiving by a programmable logic controller PLC measurement data of a process instrument, wherein the measurement data is periodically stored in a historical database, and wherein at least one virtual function module is integrated on the programmable logic controller PLC, wherein a mapping is set between at least one input channel of each virtual function module and an output of at least one anomaly diagnosis algorithm arranged on a service provision system, each anomaly diagnosis algorithm being used to diagnose whether an anomaly exists in a process instrument; upon receiving, via an input channel of the virtual function module, an anomaly indication outputted by the service provision system, the programmable logic controller PLC determines that an anomaly exists in the process instrument corresponding to the anomaly diagnosis algorithm, wherein the anomaly indication is an indication outputted when the service provision system determines that an anomaly has occurred in the process instrument after acquiring the measurement data from the historical database and using the corresponding anomaly diagnosis algorithm to diagnose the measurement data, wherein each anomaly diagnosis algorithm is disguised as an algorithm module of the PLC, such that the anomaly indication is outputted to a corresponding input channel of the PLC and the anomaly indication participates in PLC control directly as an input parameter of the PLC; and wherein the programmable logic controller PLC controls a process execution mechanism according to the measurement data when the anomaly indication is not received, and controls the process execution mechanism according to a preset default datum when the anomaly indication is received.