The invention relates to a liquid oil monitoring device adopting full-frequency-band-working-condition adaptive filtering, separating and molding. The liquid oil monitoring device is arranged on a hydraulic pipeline, and a filter, a separation and adsorption module, a rotary molding module, a detection coil, a flow sensor and a demagnetization module of the liquid oil monitoring device are sequentially arranged on the hydraulic pipeline; the detection coil and a reference coil are in series connection; an ECU is electrically connected with the filter, the separation and adsorption module, the rotary molding module, the detection coil, the reference coil, the demagnetization module and the flow sensor separately and controls the filter, the separation and adsorption module, the rotary molding module, the detection coil, the reference coil, the demagnetization module and the flow sensor; the filter is a full-frequency-band-working-condition adaptive filter; the separation and adsorption module consists of a mechanical centrifugation module, a magnetization module, a magnetic adsorption module, an electrification module and an electric adsorption module which are sequentially connected. The liquid oil monitoring device adopts a non-contact measurement mode and has the advantages of good signal consistency, high reliability, strong detection signals and small error.