Pressure loss in mixing process of rotating detonation combustor (RDC) acts as a critical barrier to system’s pressure gain performance, thereby compromising its operational efficiency when integrated into power generation systems. Based on a symmetric H₂ injection RDC, a series of numerical simulations on mixing characteristics of RDC are conducted by altering injection position and equivalence ratio. The results show that the introduction of symmetric injection and the change of its position have a significant impact on mixing characteristic parameters, while changing equivalence ratio has little effect on mixing characteristic parameters. Counter-rotating vortex pairs (CVPs) cause an increase in non-uniformity parameters and pressure loss, as well as a decrease in detonation area ratio. As equivalence ratio decreases, total pressure recovery coefficient decreases before x = 3.5 mm of RDC dome and increases after x = 3.5 mm. At the ignition zone, when the position of nozzle moves from x = 0 mm to x = −2 mm, detonation area ratio increases from 0.318 to 0.417 and total pressure recovery coefficient increases by 1.47%.