A monitoring system applied to a shaping machine having a high speed electricity meter. The monitoring system includes a current obtaining device and an analyzing device. The current obtaining device is coupled to the high speed electricity meter to obtain a plurality of current signals from the operated shaping machine and in respond to the shaping machine executes a machining program, the current obtaining device extracts current variation data from the current signals. The machining program corresponds to a piece of the current variation data. The piece of the current variation datum comprises a maximum current and an occurring time that the maximum current being recorded. The analyzing device is configured to calculate a gap, based on the maximum currents and the occurring times corresponding to at least two successive machining programs. In respond to the gap time exceeding a predetermined threshold, the analyzing device generates a warning signal.