Abstract: The counterflow jet is an important technical means for flame stability. In order to explore the effect of counterflow jet on steady burning of the reversed injection burner of coal particle combustor,the flow field structure of different annular and round jets into a counterflow were computationally investigated using the Realizable k-ε Model in Fluent platform. By computing the penetration length in variational velocity ratios of each jets,the results show that the penetration length of annular jet is larger than that of round jet,and it increases when the annular grows,The permeability of annular jet in ambient flow increases which is conductive to increase the backward propagation distance of pulverized coal and residence time and improve combustion stability. Unlike round jet,the penetration length of annular jet does not have a monotonic linear relationship with velocity ratio. There exists a smooth transition when velocity ratio between 7.5-12.5,which indicates that the decrease of velocity ratio does not cause significant decrease of penetration length within a certain interval and has guiding significance for the design of existing burners. By calculating the maximum zero velocity half-width of each jet tube at different velocity ratios,it is found that the half width of zero velocity of annular jet is wider than that of round jet,and increases with the increase of the inner diameter,which indicates larger radial expansion width and stronger suction capacity. The half width of zero velocity of annular jet increases linearly with the velocity ratio,and the slope increases with the increase of the inner diameter. The radial expansion capacity of annular jets in counterflow with high velocity ratio is stronger than that of annular reverse efflux with low velocity ratio. By plotting streamline according to the calculation result,it is found that the streamline of annular jet is similar with round jet at lower velocity ratio,At higher velocity ratio,although the axis velocity decreases to zero at the stagnation point,the fluid still propagates downstream in a certain area near the axis,and it takes some distance before the velocity drops to zero and return,the dividing streamline also becomes irregular. The circumferential flow has a certain degree of compression and obstruction effect on the annular jet in the axial direction,so that the radial expansion width of the jet increases and the suction capacity of the jet increases,which is helpful to promote the mixing of pulverized coal and combustion air in the burner. By studying the change of axial velocity along the reverse jet axis of different jet tubes,it is found that the velocity attenuation on the annular jet axis is more gentle than that on the circular jet axis,which indicates that the mixing with the environmental flow is not as strong as that of the round jet. As the inner diameter decreases,the peak value of the axial velocity of the annular jet increases and its position advances,and the attenuation velocity increases,which gradually approaches the attenuation on the central axis of the circular jet.