Objective To explore the quantifiable parameters to evaluate left ventricular（LV）regression，to analyze the effect of retraining，and to assess the results of artery switch operation.Methods 86 patients with transposition of great artery with intact ventricular septum（TGA/IVS）were enrolled. LV retraining and the second stage arterial switch operation（ASO）were performed in 43 cases，while one-staged ASO were performed in other 43 patients. LV anterior-posterior diameter （LVEDd）and Z value，LV mass index，LV pressure regression ratio，LV mass regression ratio were measured.Results The Z value of LVEDd and LV mass index strongly correlated with the ratio of LV/RV pressure. The prior parameters to determine the timing of two-staged ASO were LV mass index with a cutoff value of 59.7 g/m2 and Z value of LVEDd with a cutoff value of -1.45，with area under curve of 0.97、0.93，sensitivity of 88.9%、88.9%，and specificity of 97.4%、82.1%. Among 43 patients undergoing LV retraining，10 patients underwent ASO within 10 days after training, 31 patients underwent ASO after a mean 281.6 days, the other 2 patients underwent pulmonary artery bandings twice. Age was an independent factor of LV regression degree and only influencing factor of successful LV retraining.Conclusion LV mass index and Z value of LVEDd could judge the ratio of LV/RV pressure，and determine the timing of ASO. LV retraining is safe and could provide the treatment opportunities for the TGA/IVS patients with LV regression.