The oscillatory characteristics of a pseudo-shock wave with a Mach number of 1. 75 in a rectangular straight duct are experimentally investigated by static pressure measurements both on the duct axis and on the wall surface. The aspects of the pressure oscillation in the pseudo-shock region are analyzed from the treatment based on the intermittent characteristics, root-mean square, probability density function and cross correlation of the pressure signals. The correlation between the oscillatory characteristics and the flow mechanism of the pseudo-shock wave is also discussed in detail in the last section of the present paper.