A new firmware update I9300ZNEMB2 is now available for download. It brings Android 4.1.2 Jelly Bean to Galaxy S3 China devices. The update is currently rolling out to selected I9300 devices. You can also download the firmware zip file and install it manually using Odin or similar tool. The details about this update and direct download link can be found below:
Version: Android 4.1.2
Date: Feb 28, 2013
You can get this update via OTA update or you can install it using Samsung Kies. However, if you do not see a firmware update available, you can download it from the link provided below and flash I9300ZNEMB2 firmware file on your device.
Before installing, you need to be sure that you have taken backup of your important data. Also, this will unroot your Galaxy S3 and you will have to root it again.
Manually Install I9300 ZNEMB2 Galaxy S3 China Jelly Bean Update
Direct download link: I9300ZNEMB2_I9300CHUEMB2_CHU.zip
After downloading, follow our step by step guide: how to install stock firmware using Odin.