want doing sth的意思是：表示某物需要（应该\要求）……，相当于want to be done.
例句：
The computer wants repairing.= The computer wants to be repaired.
这台电脑需要修理。
The windows wanted cleaning.= The windows wanted to be cleaned.
窗户该擦了。
The plants want watering daily.= The plants want to be watered daily.
这些花草需要天天浇水。
类似用法还有：need\repuire做“需要”表示这两种用法。
repuire词义同 need，常可换用，但语气较弱。
The house wants/needs repairing/to be repaired.
这房子需要修葺。
This letter requires/needs to be answered at once.
此信需要立即回复。
These babies require/need careful looking after.
这些婴儿需要细心照看。
The mastery of a language requires/needs painstaking effort.
要学好一种语言，必须下苦工夫。
The door wants painting. = The door wants to be painted.
门该刷漆了。
The coat wants cleaning. = The coat wants to be cleaned.
外套该洗了。
The flowers want watering.= The flowers need to be watering.
花需要浇水了。
知识拓展
在口语中want to=wanna，想要做某事，其后 动原，一般人作主语。
I wanna drink some water.我想喝水。
He'd always want to go to Beijing.他总是想去北京。
“want sb. doing sth.”往往用于否定句，表示已经发生或正在发生的负面或消极情形，表示不希望或不愿意某人做某事。而“want sb. to do sth.”，则表示说话时还未发生的动作或情形，可以用于肯定句或否定句，也可以用于叙述正面或负面的情况，表示“想要或希望某人某事”。
I didn’t want you losing fingers over it. 我不想你为此丢了手指。电影《神奇动物在哪里》
I don’t want you ending up with a bad grade.
我不希望你最终的成绩很差。电影《生活大爆炸》
We don’t want you getting into trouble. 我们不想你遇到麻烦。
I don’t want women meddling in my affairs. 我不希望女人干预我的事。
I don't want you coming home so late.
我不希望你这么晚回家。
I want you to find out what they're planning.
我想要你去查明他们的计划。
Do you want me to help?
你要我帮忙吗？
We didn't want this to happen.
我们并不希望发生这样的事情。
I want it (to be) done as quickly as possible.
我希望这件事尽快完成。
You don't want to do it like that.
你不应那样做。
It is not clear what they want us to do.
我们不肯定他们要我们做什么。
Do you want me to ask the guv'nor about it?
你想让我就这事问问老板吗？
Do you want me to come along and hold your hand?
你想让我过去帮你一把吗？
It is not clear what they want us to do.
我们不肯定他们要我们做什么。
《牛津高阶英汉双解词典》
Do you want me to post it for you? 要我给您寄出去吗?
Don’t you want someone to go along with you? 难道你不想什么人和你一道去?
有时还可接过去分词的复合结构，表示希望某事被做了，此时通常可视为过去分词省略了to be。如：
I want the letter (to be) posted at once.
我想把这信马上寄走。
I want that letter(to be) typed today.
我想要那些信今天就打好。
We don’t want anything (to be)said about this.
我们希望不要再谈起这事了。
