The deflecting oscillation of planar opposed jets is experimentally studied and numerically simulated by large-eddy simulation (LES) at 25 ≤ Re ≤ 10000 (Re= U0hρ/μ, where U0 is the bulk velocity of the jet at the nozzle exit, h is the height of the slit of the planar nozzle, and ρ and μ are the density and dynamic viscosity of fluid, respectively) and 4h≤ L ≤ 40h, where L is the nozzle separation. The numerical results are validated by comparing with the experimental results of planar opposed jets. Maps of parameter space describing the deflecting oscillation of planar opposed jets at various nozzle separations and exit Reynolds numbers are presented. And the variation features of deflecting oscillation periods and velocity-pressure of turbulent planar opposed jets are primarily investigated. The results of the study show that the LES can effectively predict the deflecting oscillation of planar opposed jets. The velocity and pressure at specific points vary periodically while the deflecting oscillation of planar opposed jets happens. Furthermore, the variation periods of velocity and pressure are in accordance with the periods of the deflecting oscillation. In essence, the deflecting oscillation of planar opposed jets is caused by periodical variation and transformation of the velocity and pressure.