The invention discloses a testing and allocating positioning-supporting device and a separate layer water injection allocating system. The testing and allocating positioning-supporting device comprises a shell body, a magnetic induction element, a control mechanism and an actuator, wherein the shell body extends lengthwise, openings communicating to the inner portion of the shell body are formed in the side wall of the shell body, and the openings are used for allowing supporting arms to extend out; the magnetic induction element is located in the shell body, when the magnetic induction element enters a water allocating working barrel, a magnetic field changes, and the magnetic induction element generates a magnetic induction signal when the magnetic field changes; the control mechanism is connected with the magnetic induction element; the actuator is connected with the control mechanism; and the control mechanism controls the actuator to enable the supporting arms to open when receiving the magnetic induction signal. According to the testing and allocating positioning-supporting device and the separate layer water injection allocating system, when testing and allocating are conducted on a concentric separate injection well or a eccentric separate injection well, the testing and allocating positioning-supporting device can open automatically, manual control is not needed, thus the problem that butting joint of the testing and allocating positioning-supporting device and a water nozzle of the water allocating working barrel is difficult can be solved, and the success rate of testing and allocating can be enhanced effectively.