om diagnostic of dilaton dark energy with two-parameter ω in potential [1+(σ −a)2]e−bσ

based on a new geometric diagnostic method- om, we consider a new independent-model parametrization ω = ω₀ + ω₁( z /1+z )ⁿ. when we work in potential w_σ [1 + (σ −a)²]e^(−bσ), we investigate the evolutional behavior of o_m with respect to red-shift z and the influence of coupling parameter α on the trajectory of om with respect to z. we get that phantom model of dilaton dark energy can avoid the future singularity “big rip”. the numerical results give current value of eos ω_σ0 =−0.956 which fits the latest observational data wmap5+bao+sne very well.