Rectangular holes photonic crystal waveguide was proposed, by introducing rectangular holes in the second row and ellipse holes in the first and third rows near the linedefect waveguide to replace circle holes. The characteristics of slow light were investigated by plane wave expansion method. Influence of the structure asymmetry of rectangular holes to slow light bandwidth and low dispersion property were studied. Results show that within the linear region of guided mode that average group index varies at a variation of ±10% range, compared to circular holes linedefect waveguide, the obtained guided mode can be better restricted in band gap, when width parameter of rectangular holes is smaller than height parameter, guided mode can obtain slow light with bigger normalized delaybandwidth product, wider bandwidth and lower dispersion. Optimization to parameters of rectangular holes in the waveguide shows the biggest normalized delaybandwidth product about 0.402, with bandwidth about 44.4 nm and group velocity dispersion about 8.0 ps2/mm, it indicates that the waveguide has a promising application in the field of data transmission without distortion.