Abstract: Based on the Liepmann's theory of vortex sound, the sound power spectrum from the boundary layer transition recieved at the stagnation point of an axisymmetric body is analyzed and predicted by introducing the Lauchle's random indicator fUnction, and the loss in sound energy due to accoustic diffraction of the waves around the nose contour is taken into account. It is shown that the transition zone creates monopole-type sound radiation; the peak spectral energy of transition zone is shifted to higher frequncies as the streamwise length of transition zone gets smaller; and the power is dependent on the velocity greatly. The calcutated values are in agreement with the experimental data very well.