Producing the broad XUV spectra is an important way to generate the isolated attosecond pulse, in which the propagation effect is an important factor. With the first order propagation equation of the slowlyevolvingwave approximation, the propagation effect on the broad XUV continuum spectra and the isolated attosecond pulse generated by twocolor fewcycle laser pulse were investigated. By simulating the generation of the broad XUV spectra under different focal positions and different medium lengths, it was found that it is benefit for the generation of the continuum spectra when the medium is after the focal point. But, with the longer medium, the pulse duration of the isolated attosecond pulse will be longer, although its intensity becomes higher. With further analysis, it was found that if the delay between twocolor pulses can be optimized, a strong isolated attosecond pulse with the same pulse duration as that of the singleactive electron model can still be obtained.