In order to improve the fertilizing uniformity of outer–groove fertilizer by parameter optimization of fertilizer tongue, the discrete element simulation model of outer–groove fertilizer has been built to simulate the discharging working process. The simulation results were used to analyze the flow characteristic of the fertilizer particles. By using virtual test method, the effect of fertilizer tongue chamfer on fertilizer flow character has been analyzed. The results indicated that as the tongue chamfer increases, the variance coefficient of fertilizer discharging monitor mass decreases firstly then increases. There is a negative parabola quadratic function correlation between them. and the discharging amount has a least fluctuation with the best fertilizing uniformity when the ratio of the chamfer to single groove arc lengthis 0.85. The results of verify test indicate that outer–groove fertilizer with optimal structure fertilizer tongue has the smallest variance coefficient of fertilizer flow and its fertilizing uniformity is the best. Compared to the traditional fertilizer tongue with flat end, the chamfer fertilizer tongue had an reduction increase in fertilizing uniformity by 49.9%.