The invention relates to an adjustable inertia separator. The adjustable inertia separator is used for separating gas from liquid and fine grains in a gas-liquid-solid mixed medium. The adjustable inertia separator comprises a barrel and a fluid director; the barrel is equipped with an inlet end, a liquid outlet end and a gas output channel; the inlet end is used for inputting the gas-liquid-solidmixed medium; the barrel comprises an inlet part and a liquid collecting part connected with the inlet part; the liquid outlet end and the gas output channel are arranged on the liquid collecting part; the inlet part is equipped with a first end and a second end which are opposite to each other; the inlet end is arranged on the first end; the fluid director is located between the second end and the liquid collecting part; the fluid director comprises a fluid guiding cone, a plurality of guide vanes moveably arranged on the fluid guiding cone, a wall drum annularly arranged on the periphery ofthe guide vanes and a guide vane controller connected with the guide vanes; the fluid guiding cone is fixedly connected with the wall drum; the guide vane controller is used for controlling the layout angles of the guide vanes and adjusting the outlet angles and sectional areas of the guide vanes.