The invention discloses a fixture for nuclear magnetic resonance sensors. The fixture comprises a universal rod, a snap ring detachably connected to a mandrel and a support plate used for fixing one nuclear magnetic resonance sensor. An included angle of a first connecting rod and a second connecting rod of the universal rod can be adjusted through a first hinge at the end, and relative position of the first and second connecting rods is locked through a first locking mechanism. An axis angle of the snap ring and the first connecting rod can be adjusted through a second hinge and locked through a second locking mechanism; an included angle of the support plate and the second connecting rod can be adjusted through a third hinge and locked through a third locking mechanism. The fixture is simple in structure, small in size, lightweight and strong in flexibility, fixation and detection of the nuclear magnetic resonance sensors are facilitated greatly, and the fixture is adaptable to independent detection on cluster parachutes at different positions of composite insulators on engineering sites.