C/SiC复合材料在化学气相沉积（CVI）过程中不可避免地会产生孔隙、微裂纹和分层等缺陷，超声能量衰减极大，组织极不均匀，几乎看不到二次底波，用常规的多次底波法无法测量其声速，提出了一种利用信号处理中的相关原理来测量其声速的方法，并用MATLAB软件进行了仿真以验证该方法的可行性。结果表明，利用相关法测量6种材料的声速，其误差均在2.5%以内，因此利用这种方法测量C/SiC复合材料的声速是可行的，对于C/SiC复合材料的声速测定有很大的实际意义。

There inevitably exist defects such as pores, microcracks and delamination in C/SiC composites during CVI deposition, resulting in material anisotropy, great acoustic attenuation, and extremely non-uniform microstructure. Therefore, there is hardly any secondary bottom wave appearing during the ultrasound echo test for this material, and the sound velocity cannot be measured by the conventional multiple bottom wave method. This paper proposes a method to measure the sound velocity by using the correlation principle in signal processing, and simulates it with MATLAB to verify the feasibility of the method. The experimental results show that the sound velocity of the six materials is measured by the correlation method, and the error is within 2.5%. Therefore, it is feasible to measure the sound velocity of a C/SiC composite by this method. It has great practical significance for the determination of sound velocity of C/SiC composites.