The statistic specimen used by this paper is collected by track geometry inspection car from Bogl slab track of Beijing-Tianjin intercity high speed railway. Based on the stationary test of the specimen, Fast Fourier Transform (FFT) method is used to evaluate the spectrum of the whole specimen space. The power spectrum density (PSD) is obtained by MATLAB program. The specimen is equally divided by twelve parts, and the coefficients of track profile irregularity and track alignment irregularity are analyzed. The results show that the 1.1∼1.5 m periodic waves in rail gauge irregularity, track alignment irregularity and track profile irregularity are obvious. The 3.0 m periodic waves in rail gauge irregularity, track cross level irregularity, track alignment irregularity and track profile irregularity are very apparent. The 5.0 m periodic wave in track alignment irregularity and 6.0 m periodic wave in track profile irregularity are remarkable. There exist obviously 50 m periodic waves in track alignment irregularity. The left rail profile irregularity and right rail profile irregularity are controlled very well, but the left rail alignment irregularity and right rail alignment irregularity still need to be improved in some sections.