画蛇添足 paint a snake and add feet
Explanation
画蛇添足，比喻做多余的事，非但无益，反而不合适。
This idiom is a metaphor for doing something unnecessary, which not only does not benefit, but also is inappropriate.
Origin Story
从前，楚国有个专门负责祭祀的官员。每年春天祭祀完后，他都要倒一杯酒给手下人喝。由于人多酒少，不够分，于是他就想了一个主意，谁先画好一条蛇，谁就先喝一杯酒。有个官员第一个把蛇画好了，他看见别人还没有画完，就得意洋洋地在地上画了条蛇，然后就在蛇的旁边画了两只脚。可是画完后，他就发现自己好像做错了什么，因为蛇是没有脚的。这时，他突然醒悟到，自己做了一件多余的事，于是就懊悔地自言自语道：“哎呀，我画蛇添足了。”
Once upon a time, there was an official in the ancient kingdom of Chu who was in charge of sacrifices. After the spring festival, he wanted to pour a cup of wine for his subordinates to drink. Because there was not enough wine, he came up with an idea: whoever drew a snake first would get a cup of wine first. One of the officials drew a snake first. He saw that the others had not finished drawing, so he smugly drew a snake on the ground and then drew two legs next to the snake. But after he finished drawing, he realized that he had done something wrong because snakes do not have legs. Then he suddenly realized that he had done something extra, so he regretted and said to himself:
Usage
画蛇添足比喻做了多余的事，非但无益，反而不合适。例如，在工作中，如果你在已完成的任务上添加了不必要的东西，可能会适得其反。
The idiom "to paint a snake and add feet" is used to describe an unnecessary action that not only does not benefit, but can even be harmful. For example, in the workplace, if you add unnecessary things to a task that has already been completed, it may backfire.
Examples
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你这种做法，简直是画蛇添足，毫无意义。
ni zhe zhong zuo fa, jian zhi shi hua she tian zu, hao wu yi yi.
Your approach is simply pointless.
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在本来已经很完美的计划中，再加入一项新的措施，只会是画蛇添足。
zai ben lai yi jing hen wan mei de ji hua zhong, zai jia ru yi xiang xin de cuo shi, zhi hui shi hua she tian zu。
Adding another measure to an already perfect plan would only be a step in the wrong direction, it would only unnecessarily complicate it.