they should be in imageformats directory

What you mean? I need to create a sub directory called imageformats relative to my exe file folder?

Yep and move these libs to this dir.

What I want is put evarything in release folder and release the folder to other PC which nol Qt library installed.

I have moved to the dll files but still no luck.

My directory structure is:

In release/,

myApp.exe
QtCore4.dll
QtDeclarative4.dll
QtGui4.dll
QtNetwork4.dll
QtScript4.dll
QtSvg4.dll
QtSql4.dll
QtXml4.dll
QtXmlPatterns4.dll

in release/imageformats

qgif4.dll
qico4.dll
qjpeg4.dll
qmng4.dll
qsvg4.dll

What is wrong?

all looks ok. Are you sure your problem is in not-loaded image plugins?

I copy the contents of imageformats to plugins/imageformats relative to the exe, and create a qt.conf file.

Directory structure:

qt.conf

I tried it but no luck. I use the depends.exe to profile it and found it said can not open wintab32.dll. But I searched my PC and can not find it.