In order to improve the complicated fabrication process and integration of 3D micromixers, we propose a novel planar self-stirring micromixer with high mixing efficiency and low pressure drop. The planar micromixer with vortices agitation for mixing enhancement had been successfully investigated by the Taguchi method, CFD-ACE simulations and experiments. The factor sensitivity test was performed by L9(34) orthogonal array in Taguchi method. Degree of sensitivity ranks as: Gap ratio > Number of mixing units > Baffle width > Chamber ratio. At Re = 20, micromixer shows 93% mixing efficiency in the adaptive design with three mixing units, H/W = 1/8, W m/W = 1 and Wm = 80. The corresponding pressure drop of this adaptive design is only 4600 Pa at Re 20. Much improved mixing is obtained experimentally in this adaptive design at Re 20. The results of the factor sensitivity test can provide useful information for the design of the micromixers with obstacles. Merits of this design are easy fabrication and high integration capability.