In view of the difficulty of accurately extracting voltage flicker envelope and real-time estimation of flicker parameters in new power system, the improved the square detection method is used to accurately extract voltage flicker envelope, and construct adaptive TLS-ESPRIT algorithm based on adjacent singular value ratio to extract frequency information of envelope signal. The flicker frequency formula of adaptive TLS-ESPRIT algorithm is derived, and the flicker amplitude information is calculated. Based on this, a flicker parameter detection method based on improved square detection and adaptive TLS-ESPRIT is proposed, and an experimental platform for voltage flicker parameter detection based on virtual instrument is developed. Simulation experiments show that the proposed algorithm can effectively estimate voltage flicker parameters under noise and harmonic interference, and can effectively overcome the influence of single-frequency and multi-frequency amplitude modulated wave modulation and power grid fundamental frequency offset. Compared with the traditional voltage flicker parameter detection algorithm, the proposed algorithm has simple calculation and small flicker parameter detection error.