I AM SAUDI NATIONAL AND I HAVE A VALID ENTRY VISA TO CHINA BUT MY PASSPORT WILL EXPIRY 30/01/2012

Yes, you can still enter China with your passport on July 10, 2011. Once you get a valid China visa, you can enter China when your passport is still valid. The passport with at least 6 months validity is required when you apply for China visa. After you obtain the visa, you can still enter China even though your passport doesn't have 6 months remaining validity.