The dual-mass double-linear vibrational gyroscopes are insensitive to the environment, and their differential outputs can effectively suppress the common mode interference. A structure-decoupled dual-mass MEMS(micro-electro-mechanical system) gyroscope is studied in this paper, which can realize the full decoupling of the driving mode and sensing mode. In order to improve the performance of the dual-mass MEMS gyroscope, a self-adaptive closed-loop detection method is developed. This method tunes the sensing-mode frequency to driving-mode frequency, achieves the driving and sensing modes matching, regulates the amplitudes of the sense axis to a constant value. The results of simulation and experiment indicate this self-adaptive closed-loop detection method makes the sensing mode oscillate in a given frequency and the amplitude to a fixed value for dynamic range and precision improvement. This detection method achieves translational acceleration elimination, cancels out quadrature error, improves the gyro's total performances and achieves the ideal design purpose.