I have tried to install the latest version 1.2.1. Everything is OK, the backend can be displayed in Chinese without any problem. However, when I try to config the gallery, I found that Chinese characters cannot be input in fields such as Gallery title. Most characters were trimmed after applying the change. So I used phpmyadmin to edit the fields manually. This method worked, the backend can show the edited fields. So I think there is a problem for this version to store Chinese characters.

I heard many sucussful case to use zenphoto in Chinese. Therefore, I downloaded the old v1.2 and installed under the same database. This time, the problem disappeared.

Does anyone know the cause of the problem?

Please try the nightly build / svn version if the problem dissapears there.

thanks for your reply, I just found out a similar situation at this thread: http://www.zenphoto.org/support/topic.php?id=4035

the nightly build (2008-10-13) has solved the problem.
although the install process explicitly suggest to add

[mbstring]
mbstring.internal_encoding = UTF-8 ;

in php.ini, the problem does not occur with our without the above modification. Hope the next stable release will take note of this. Thanks~

The release will suggest setting the mbstring.internal_encoding as it did for you. That is not something that zenphoto should be doing unilaterally as it will effect all scripts you run. So each individual will need to carafully consider whether to make the change or not.