As cylinder-segment scatters have the features of anisotropy and multiple controllable degrees of freedom. With the plane-wave expansion method, the slow light effect with high group refractive index and low dispersion can be generated by optimizing the structures of photonic crystal waveguide with line defect, such as changing the length of major axis or minor axis, or rotating scatterers relative to the direction of line defect. Simulation results show that slow lights with band width from 10.1 nm to 1.1 nm and group refractive index from 36.5 to 287.5 are achieved by changing the lengths of major axis or minor axis; slow lights with band width from 11.4 nm to 0.8 nm and group refractive index from 45.5 to 293.7 are gained by rotating scatterers. Moreover, slow lights with ultralow dispersion, even near zero dispersion, can also be obtained by these methods, which shows that choosing suitable scatterers and adjusting their parameters can efficiently achieve slow light effect with high group refractive index and low dispersion.