新官上任三把火
a new official introduces a rash of changes; a new broom sweeps clean
e.g. 俗话说新官上任三把火，新来的主任决心干几件事，使车间改变面貌。
As the old saying goes, "a new broom sweeps clean", the newly-appointed manager is determined to adopt several measures and give the workshop a new look.
