The active regeneration characteristics of cordierite DPF in the drop-to-idle(DTI) process were studied based on diesel engine test bench. The effect of soot load on DTI regeneration temperature characteristics and the transient emission characteristics of DPF after DTI test were investigated. The results showed that the temperature distribution inside the filter was very uneven during the DTI regeneration process and the peak temperature appeared at the middle part of the rear end of DPF. The soot load had a significant effect on DTI regeneration temperature and PM and PN emissions. When the soot load was 7 g/L, the peak temperature reached 1 394.1 ℃, and the maximum temperature gradient reached 139.0 ℃/cm. PN emission exceeded the China Ⅵ limit by more than 10 times, while PM emission increased significantly and still met the China Ⅵ limit within a large margin. When the tolerance temperature and temperature gradient of cordierite ceramic materials exceeded the limit, the DPF had a great risk of melting and cracking. Therefore, it was necessary to select a reasonable limit of regeneration soot load to ensure the DPF reliability.