Xiang Li

Why is this a problem?  I don't understand what the problem is here.  If I use your expression as a test:

It picks up the first character and this is enough for me to filter on only the Chinese rows.  I think you need to explain a little more what the issue is, preferably with an example file, or text.

Hi, Paul

If I use this regex, the first character of each Chinese line will lost

This is the original file

and this is the preview in trados

As you can see, the first Chinese character is missing.

Try this opening pattern:

^(?=[\u4e00-\u9fa5])

And the same closing pattern:

$

Xiang Li

ok - now I understand what you mean.  Very strange.  I open the file in Studio and see this:

I filter and I see this:

No chars missing.  However, I also see that you didn't mean filter at all... you created a filetype rule that says this:

So the filetype has done exactly what you asked it to do.  It excluded what it found.

If you use the same expression in the Advanced Display Filter then you will get exactly what you wanted.

If you are determined to solve this using a custom filetype then use this rule instead

(?=[\u4e00-\u9fa5])+

$

Then you get this:

I don't actually want to capture Chinese chars as this will exclude them in this feature.  So instead I just use a positive lookahead to verify they are there and if they are I extract the segment.

The regex works， thank you

You are right,I created a specific filetype to phase the file, it's a js file, a 7 Megabytes complex js file , I have to divide it into many parts to phase it. 

Fortunately, almost all the rows that need to translate are start with Chinese characters.