Abstract: The purpose of the paper is to study cross-phase modulation of pulse pairs with different shapes in optical fibers with quintic nonlinearity.Starting from the extended coupled nonlinear Schrdinger equations including quintic nonlinearity,the expressions for the nonlinear phase shifts and frequency chirps of different pulse pairs were derived,and the phase shifts,chirps and power spectra of pulse pairs with different shapes were simulated,compared and analyzed.The results show that,the powerful negative quintic nonlinearity can greatly influence the central regimes of the curve shapes of the phase shifts,chirps and spectra.While the positive quintic nonlinearity(weak negative quintic nonlinearity) can only increase(decrease) the phase shifts,chirps,the spectral width,and the number of spectral peaks.The soliton pairs are similar to Gaussian ones in terms of their spectral shapes.Depending on the quintic nonlinearity coefficients,the spectral peaks with the maximum energy may distribute in the vicinity of the center or near the edge.The super-Gaussian pairs are also similar to each other in terms of their spectral shapes.But the energy remains mainly on the central peak.To some degrees,this investigation may contribute to the pulse compression,optical switching devices and improving the performance of optical fiber communication systems,etc.