An etched diffraction grating wavelength router (EDGR) with arc-shaped grating teeth is proposed,and the loss uniformity and spectral passband of the device can be improved simultaneously with proper design for the shape of the grating teeth. A 4×4 EDGR with 400 GHz channel spacing, centered at 1550 nm and based on InP platform is designed. Simulation results show that the loss difference of all channels is reduced from 8.1 dB to 0.8 dB. The shape of the spectral response is flat-top and the 1 dB bandwidth is increased from 0.3 nm to 1.6 nm. By adjusting the design parameters, the loss uniformity, bandwidth and entire loss of the device can be balanced. Experimental results show that the loss difference of all channels is 3.1 dB and 1 dB bandwidth is 1.1 nm. The crosstalk of the device is better than -12 dB. The validity of this method is verified. This method does not need to increase the chip size or add extra elements, which can be applied to etched diffraction gratings in any material platform.