脱胎换骨　

◎ 脱胎换骨 tuōtāi-huàngǔ

[be reborn;change completely and thoroughly;create new things out of the old;turn over a new leaf] 道教徒认为人在苦修得道之后,就能脱下胎,换上骨。现在常用来比喻痛改前非,重新做人