The invention provides a separation apparatus and a supercritical reaction system with the same. The separation apparatus comprises a material input pipe and a shell with a preset inner diameter, wherein the material input pipe is arranged and connected to the top of the shell in a penetrating manner, the material input pipe extends in the shell, and a first preset distance is reserved between a discharging end of the material input pipe and the bottom of the shell; a solid phase outlet is formed in the bottom of the shell; and an output opening is formed in the side wall of the shell. By adopting the shell with the preset inner diameter, the speed of a material input by the material input pipe is decreased, so that the material is stable in motion; and in the process that the decelerated material moves to the top of the shell under the pressure difference, solid particles in the material are separated from other phase substances under the gravity effect, so that the separation of the solid particles in the material is realized, the operation is simple, and the separation effect is good. Moreover, the separation apparatus is not only suitable for separating low-temperature low-pressure materials, but also suitable for separating high-temperature high-pressure materials.