In order to study the influence of trailing edge symmetrical jet on leading edge vortex breakdown location and flow structure over a delta wing, vortex flows over a 60oswept delta wing with trailing symmetrical edge jet and without trailing edge jet were studied using high precise simulation of N-S equations. The results show that the ratio of jet velocity to free flow velocity affects the location of vortex breakdown. Compared with the condition without jet, the variation of the ratio of jet velocity to free flow velocity determines vortex breakdown location advance or delay. The difference from the traditional opinion is that not every case with trailing edge jet could delay the location of vortex breakdown. In addition, the trailing edge symmetrical jet has little influence on the position of the vortex axis. The trailing edge jet does not change the rule of topological structure transformation of the cross section, but it impacts the velocity of limit ring spread.