i have 3d gimbal system and i want to use this sensor in place of IMU(3 axsis accelerometer) in Quadcopter
A gimbal system will not replace an accelerometer. I assume by gimbal system you mean something like a Gyroscope, i.e. a device that has a fixed orientation allowing you to measure your orientation relative to it.
A gyroscope can give you information on orientation and possibly angular velocity. An accelerometer gives you information on acceleration/gravity. Since the accelerometer can identify the direction of gravity using a couple simple assumptions, you can also use it to estimate your orientation.
Final answer: a gimbal/gyroscope can replace an accelerometer for the purposes of calculating the orientation of a device/quadcopter, a gimbal cannot replace the full functionality of an accelerometer.