Abstract: Ionization involving the charge transfer and single capture processes, in Xq++B (X=C, O；q=1, 2；B=Ne, Ar) collisions in medium-low energy were investigated using the ion beam of accelerator by the position sensitive and time-of-flight techniques. The experimental results indicate that for a given charge state of the incoming projectiles the ratios R of the transfer ionization to single capture change strongly with the projectile energy and correlate to the direct single-electron ionization in the collision. Meanwhile, the peak-position of R is formulated through the experimental analysis, the theorical calculation and the model comparison.