Provided is a double-arm self-adapting fixture used for controlling machining deformation of a blade. The double-arm self-adapting fixture is composed of a fixture connecting assembly and a double-arm self-adapting fixture body. The fixture connecting assembly and the double-arm self-adapting fixture body are connected and fixedly connected to a turning worktable of a machine tool. The fixture connecting assembly is composed of a rotary connecting disc, a quick-changing fixture base and a quick-changing fixture tray. The rotary connecting disc, the quick-changing fixture base and the quick-changing fixture tray are connected to each other and fixedly connected with a fixture body of the double-arm self-adapting fixture body. The above double-arm self-adapting fixture body is composed of the fixture body, cantilever pressing plate assemblies, a lower cantilever, an upper cantilever and blade compression screws. The cantilever pressing plate assemblies are fixed at two ends of the fixture body. The blade compression screws are screwed into corresponding positions of the cantilever pressing plate assemblies. The e blade compression screws and the cantilever pressing plate assemblies are fixed into two holes of the fixture body. The double-arm self-adapting fixture used for controlling machining deformation of the blade has following beneficial effects: six freedom of motion is provided for cylindrical tenons at two ends of the blade or a cylindrical fixture by utilizing a double-arm swing mechanism, thereby realizing the self-adapting fixture featuring unstressed reinstallation and continuous machining without a remediation benchmark after deformation of a blade machining process.