A flow cell and a liquid chromatographic unit are provided. The flow cell includes a housing, a cell core, a liquid-core waveguide, an inlet connection assembly and an outlet connection assembly. The cell core is provided in the housing, and is provided with a liquid feed recess, a liquid channel and a liquid discharge recess therein. The liquid-core waveguide is provided in the liquid channel. The inlet connection assembly is provided at an end of the cell core, and includes an inlet press block, a liquid feed tube, and a light entering tube. The outlet connection assembly is arranged at another end of the cell core and is provided with a light exit hole.