Your visa in the expired passport is still valid and you just need to show both passports when entering China.
I don't believe a Chinese visa can be transferred. You would need to apply for a new one. If applying for a new visa you may be required to present your old passport so the valid visa in it can be cancelled .
From China Embassy in USA: China Embassy in USA
Q: I renewed my passport recently. I previously had a Chinese visa on my expired passport which is still within the valid period.Do I need to apply for a new visa?
A: Please check whether there is any change of Name, Gender, Date of Birth and Nationality between the new and expired passports. If the information above has not changed and the purpose of your upcoming trip to China is consistent with the visa type, a new visa is not required. Please travel to China with both passports. If your personal information has changed or the purpose of your trip to China is different from the type of current visa, please apply for a new visa.
From China Embassy in Thailand: China Embassy in Bangkok
The Phuket Consular Office of The Consulate General of The People's Republic of China in Songkhla
Vice Consul General and Head of The Phuket Consular Office: Ms. WANG HUIJUAN
Add.: 96/69 Royal Place, By Pass Rd., Kathu District, Phuket, Thailand
Tel. No. For Visa Application Inquires: 0066-76-304180
Fax:0066-76-304302
The Phuket Consular Office has been opened since Nov.6th 2014. The Chinese visa services is available now.