In this paper, we propose a method for detecting the center wavelength of ultra-weak chirped fiber Bragg grating (uwCFBG) with jittery spectrum, based on the solution of correlation coefficient. We establish a mathematical model for uwCFBG by superimposing segmented step Gaussian functions with noise. Then, analyze the variation trajectory of the correlation coefficient under different relative positions through simulation. Finally, a comparative analysis is conducted on the 284 elements uwCFBGs. The experimental results show that the extreme difference of the center wavelength calculation is 0.19 nm and the variance is 0.08, which proves that the proposed algorithm process is simpler and the results are more robust.