Abstract: The ultrasonic testing signal of titanium alloy is always immingled with the scattering noise.According to the phenomena,this paper presents a kind of signal model of ultrasonic testing for titanium alloy and a wavelet transform denoising algorithm based on modulus maximum.The characters of producing mode and wavelet transform of noise and signal are discussed.The processing of the algorithm is followed:firstly,ascertain the location of signal in the low frequency coefficient of wavelet transform;secondly,find corresponding frequency in formation in the high frequency coefficient;thirdly,reconstruct the signal through inverse wavelet transform.Examples prove that the model can reflect the character of the ultrasonic signal and noise correctly,and the result of the denoising using this algorithm is satisfactory.