| Country: | CHN |
| Type: | G |
| Route: | 666 |
| Length Km: | 141 |
| Terminus A: | Jingtai County, Gansu |
| Terminus B: | Lanzhou, Gansu |
| Previous Type: | G |
| Previous Route: | 665 |
| Next Type: | G |
| Next Route: | 667 |
China National Highway 666, also known as the Jingtai-Lanzhou Highway, is a national highway in China, which connects Jingtai County and Lanzhou in Gansu.[1] The highway is long.[2]