A mathematical model for the power spectrum density function of dynamic speckles was established to complete the nondestructive measurement of a diffuse target. First, the dynamic speckle characteristics formed by the reflection space of a rotating cylinder at an immobile angular velocity were discussed when it was fully illuminated by a collimated light beam. The theoretical model on the cross-correlation function and the power spectrum density function of dynamic speckle intensity fluctuation was given and the coherent length and receiving signal bandwidth of the dynamic speckle field were described. Then, the impacts of speckle translation and speckle boiling caused by rotation cylinder on the received signal bandwidth were analyzed. Finally, the near-specula of the cylinder and the diffuse speckle patterns were measured. Obtained results indicate that when the wavelength of 0.633 μm is shone on the cylinder with a diameter of 1 mm, the correlation time of autocorrelation function is 4 ms for a 10 Hz rotating cylinder and 2.0 ms for a 20 Hz rotating cylinder. In conclusion, the Doppler effects and speckle translation effects in the speckle dynamic field can produce the bandwidth with the same order of magnitude, and the speckle boiling effect can be negligible.