The invention belongs to the technology of high-precision angle measurement and relates to a device and method for improving the measurement precision of a rotary table dynamic angular position error. The device comprises an angle measurement sensor, a highly-stable external synchronous clock, a servo motor control system, and a servo motor. The angle measurement sensor is formed by a spatial four-frequency differential laser gyroscope and a control circuit thereof. The angle measurement sensor and the servo motor control system of a detected rotary table are synchronized by a highly-stable clock signal. The servo motor control system and the high-precision angle measurement sensor transmit high-speed angular increment information thereof to a PXI measurement and control system. The PXI measurement and control system outputs dynamic angular position error information. By means of a manner that the PXI measurement and control system and a motor control system are deeply coupled, a dozens of MHz synchronizing clock between the PXI measurement and control system and the motor control system, and high-speed phase-locked loop technology, the device and the method control the clock misalignment and clock jitter of the PXI measurement and control system and the motor control system to be a magnitude of nanoseconds, and achieve super-speed and high-precision synchronous measurement of rotating angle dynamic errors.