The invention discloses a system for synchronous on-line detection of adsorption spectrum and fluorescence spectrum. The system consists of a reciprocating plunger pump, a sample introduction device, an enrichment device, a detection cell, a light source, a spectrograph, an optical fiber, a computer and a data processing system, wherein the sample introduction device is provided with a six-way valve; a sample passes through the reciprocating plunger pump according to a predetermined time, enters an active carbon enrichment column through the six-way valve and is discharged after online enrichment; after finishing enrichment, the six-way valve is switched; an eluate enters the active carbon enrichment column through the six-way valve; an enrichment substance is washed and enters a flow cell and is discharged after spectrum detection is performed on the enrichment substance; the content of the sample is calculated based on the change of spectrum intensity; and the flow cell is integrally connected with five-way valve formed by a light source radiation optical fiber interface hole, an ultraviolet visible light optical fiber interface hole, a fluorescence spectrum optical fiber interface hole, a liquid inlet pipe hole and a liquid outlet pipe hole. The system realizes the on-line detection of the adsorption spectrum and the fluorescence spectrum; and an instrument has the characteristics of small volume, light weight, good reproducibility, convenient carrying, and fast sample treating speed, so the system has wide application fields.