Traditional ultrasonic echo time-delay estimation algorithm is studied in the background of Gauss Noise, while in actual working condition ultrasonic echo includes not only Gauss Noise but also impulsive noise (α noise with stable distribution), which will invalidate traditional algorithms. In actual application, in order to solve the above problem, a new ultrasonic echo time-delay estimation method under mixed noise, especially the background containing α noises, was proposed, called time delay estimation algorithm with normalized cyclic correlation. Firstly, a brief introduction to theory of such normalized cyclic correlation algorithm was given and a theoretical derivation analysis on such algorithm was conducted.Then,combined with simulation analysis,the performance of proposed algorithm and traditional cyclic cross-correlation algorithm were compared under the same condition. At last, the estimation performance of such normalized cyclic correlation time delay estimation algorithm was analyzed under different singal-noise ratios. Contrast test indicates that when α approaches to 1, the cyclic cross-correlation algorithm is unable to estimate the time delay, while the normalized cyclic cross-correlation algorithm still maintains the deviation at 0.4 μs; and under -10dB SNR, the time delay estimated by normalized cyclic cross-correlation algorithm is also maintained within 10 μs. The normalized cyclic cross-correlation algorithm proposed in the article is able to make accurate estimation of time delay of ultrasonic echo under the background of mixed noise, especially the one contains α noise, which is an incomparable advantage that traditional algorithm is unable to counteract.