Aiming at problem of low practicality of existing ultrasonic echo parameter estimation method for ultrasonic detection,improve preprocessing for ultrasonic echo signal and reduce the amount of data processing,an improved method is proposed based on Gauss model for ultrasonic echo and expectation maximization( EM)algorithm. The new algorithm can not only overcome shortcoming and improve convergence speed of EM algorithm,but also achieve a higher precision. Numerical simulation and application experiment are ...