In the present study, the transmission characteristics of ultrashort pulses through coupled-cavity waveguides in one-dimensional photonic crystals were investigated theoretically, using finite-difference time-domain and transfer matrix methods. By controlling the configuration of the waveguides, a flat defects' band can be obtained in the transmission spectra, which can be used for passing ultrashort pulses. The conditions for achieving a flat defects' band are derived by optimization geometrical parameters of the waveguides. The optimized structure is able to transmit ultrashort pulses, up to 30 fs, with negligible distortion and attenuation. Unlike the previously designed waveguides with the same application, we designed our system without using graded index materials or many thin film layers.