A multifunctional on-line combination device for temperature and pressure increase-assisted extraction, trapping, and chromatographic separation, comprising four chromatographic pumps (16, 21, 22, 23), three three-way mixers (13, 14, 28), two six-way switching valves (11, 12), a temperature and pressure increase-assisted extracting unit (24), a trapping column (15), a chromatographic column (32), detectors (33, 34), etc. By on-line combining a trapping-desorption-switching device and an extraction-chromatographic separation device to control the switching of the two high pressure six-way switching valves (11, 12) and the pressure adjustment of back pressure regulators (26, 27), it is possible to automatically realize free combinations of two extraction forms, i.e. supercritical fluid extraction and accelerated solvent extraction, and two chromatography technologies, i.e. supercritical fluid chromatography and high-performance liquid chromatography, increasing the functional diversification of the device, bein
