Aiming at the problems such as low measurement aceuraey of the existing Hall Angle sensors ,basedon the exploration of the of Hall elfect prineiple and the relation between Hall voltage and magnetie fielddirection,an Angle sensor based on Hall elfect is designed. We have self.made a small Helmholtz coil toprovide a stable magnetie field, fixed the Hall probe on a support frame, and achieved high-precisionmeasurement of the angle by measuring the Hall voltage after the Hall probe rotates at different angles.Themaximum measurement error is 0. l° when the rotation angle is not more than 75°.The sensor is applied toexplore the compound pendulum motion , obtaining the image of the relation between angular displacement andtime , achieving aecurate measurement of the motion state of the compound pendulum.The error between themeasured swing period and the theoretical value is only 2.0%6 , proving that the device can achieve high-precision angle measurement with fast response.