In spectral resolution enhancement the linear prediction of exponentially decaying sinusoidal superposition signal is one of the key technologies. In this study, the direct calculating equations of forward and backward linear prediction coefficients, the relationship between forward and backward linear prediction coefficients, and the forward and backward linear predictability conditions are derived. It is shown that, for exponential decaying sinusoidal superposition signal, there is not simple conjugate symmetry between forward and backward linear prediction coefficients, but they are still related. This research provides a theoretical basis for spectral resolution enhancement about decaying interference signals.