It was returning 500 error which I couldn't find answer from document.
And we just have tested in different ways 10 mins ago.
it's weird that seems it works now, but is unstable:
I. 3 chinese fonts which are 20mb, 15mb, 5mb in a document ==> pass
II. 2 chinese font which is 20mb==> pass
III. 1 chinese font which is 5mb==> fail (Pdfcrowd Error:  Sorry, we can't process your request)
It's weird those 3 fonts are .TTF x2 and .OTF x1, it works when 3 of it in a generation, also is working in .TTF x1 and .OTF x1, but not working in when only a .OTF font.(we have tried this 3 times fail)
Also, we found and have tested this web page:http://www.allenj.net/?p=1732
this page is with the same chinese font that we got fail, but it works!!! it generates sucess!
Anyway, this is the code about the fail font that we used in the fail test:
Please help, we are going to build a paid download service, we structure users datas and users get download permit once they have paid, this is important that the payment mathod we are going to use is by mobile phone, which means if a paid user get nothing or error, we will got money loss from the telephone service share.
More, my engineer asks if it is possible we can have chinese font file stored in your server? this does help our server get much lower data transfer, we will have only 4 files when our service gets online. Is it possible in your pay service?