The combined effects of high-order dispersion and saturable nonlinearity on modulation instability induced by cross-phase modulation of two optical waves are investigated based on the coupled nonlinear Schrdinger equations including saturable nonlinearity and high-order dispersion in optical fibers. And the method of linear-stability analysis is adopted. The results show that, when the fourth-order dispersion has the same sign as that of the second-order one, a new gain spectral regime called the second gain spectrum which is far away from the zero point may appear. It actually consists of two small spectra which are always linked together. The first gain spectrum has nearly the same peak value as that of the small spectrum close to the zero point of the second gain spectrum. In the other dispersion regimes, the gain spectra consist of only one regime. The existence of the saturable nonlinearity will make the spectral width and the peak gain of every spectral regime increase with the input power before decreasing. That is to say, for every spectral regime, this may lead to a unique value of peak gain and spectral width for two different input powers.