Where could I exchange dollar to chinese yuan best way in Guangzhou?

If you are going to change your money, the best choice is to go to the Bank of China, where you can get a reasonable rate.

There are many branch offices in the city. Here list some for your reference.
Located at No. 1083 Kangwang Road.
Located at No. 215 Middle Jiangnan Avenue.
Located at No. 809 East Binjiang Road.

Apart from exchanging currency at airport and a reliable bank like Bank of China, the United Money Exchange is recommended. I know several branches of it:
1. no. 133, West Huanshi Road, Liwan District;
2. no. 161, West Linhe Road, Tianhe District;
3. 1F, no. 57, 1st Street, Huale Road, Yuexiu District.
May help!