As far as i can see there's no correct text info in that pdf (at least Acrobat can't seem to extract the text either)

Created attachment 139365 [details]
data

The data is chinese， i can view the pdf data via the microsoft edge browser.
My computer system language is chinese.

You can view the PDF too using a poppler based viewer (okular, evince, pdftoppm).

That doesn't mean you can extract the text. It's two completely different things

I download the evince, the file could be viewed by evince.
Could you tell me why it could not be extracted by pdftotext?

I know the file can't be extracted under the following scenes:
1. The word is drawed by line, not word.
2. The font type is fontTrueType or fontTrueTypeOT, the character set is same as system character set.

But in this case, the font type is "fontCIDType2 Identity-H BFAIEF+SimSun-GBK-EUC-H", I think it should by extracted correctlly.
====================================================
gs /GS1
exec op gs
  gfx state dict: << /OP false /OPM 1 /SA false /SM 0.02 /Type /ExtGState /op false >>
BT
exec op BT
Tf /TT2 1
exec op Tf
 opSetFont args[0].getName=TT2
  font: tag=TT2 name='BFAIEF+SimSun-GBK-EUC-H' 1
Tm 16.0751 0 0 16.0751 167.949 734.655
exec op Tm
cs /Cs6
exec op cs
scn 0.019608 0.003922 0
exec op scn
Tc 0
exec op Tc
Tw 0
exec op Tw
Tj (ɩ
exec op Tj
font doShowText key=TT2 name=10 Identity-H BFAIEF+SimSun-GBK-EUC-H
ET
exec op ET
q
exec op q
i 1
exec op i
===============================================================

By default, poppler think the character is UCS-4 in operation TJ, maybe in this case， the character is other, cause extracted uncorrectlly. 

The attachment is debug information of the pdf file by poppler.

Created attachment 139392 [details]
debug information of pdf file by poppler

Sorry, I don't really have time to explain to you how pdf files work.

I've not been able to find any other PDF viewer (neither the one from the people that invented PDF itself) out there that can extract the text from that file, so i'd say it's just the file being broken.

If you can extract the text with some PDF tool or even better provide a patch i'll be happy to review it.

This bug report contains markup which cannot be properly exported by Bugzilla, making it generate invalid XML. As it seems the result is that this bug will not be taken forward, I'm closing it now rather than migrating it to GitLab.