Taking into account the second- to the fourth-order dispersion and the quintic nonlinearity of an optical fiber, the synthetical effects of the fourth-order dispersion, the quintic nonlinearity and the input optical power on modulation instability induced by cross-phase modulation of two optical waves are investigated. The results show that, in case of high-order dispersion, the positive and negative quintic nonlinearity also intensifies and weakens the cross-phase modulation instability, respectively. The third-order dispersion does not influence the gain spectra of cross-phase modulation instability. When the fourth-order dispersion has the same sign as the second-order one, the existence of the fourth-order dispersion makes a new gain spectrum called the second one appear. And the second gain spectrum actually consists of two small spectra which are always linked togather. The first gain spectrum has nearly the same peak value as that of the small spectrum closing to the zero of the second gain spectrum. With the increase of the input optical power of one of the optical waves, from being separated from each other to drawing near, the two spectra merge into single one eventually, and the peak numbers of the gain spectra also become two from three. In the second gain spectrum, the peak value and the width of the small spectrum which is closing to (far away from) the zero are comparatively smaller in the normal (abnormal ) dispersion region. In the other dispersion regions, there exists only the first or the second spectral region.