Abstract: An experiment on planting density of purple sweet potato cv. "Longjinshu No.1" was carried out. The results showed that there was coordinated growth between up-ground and underground part when plant density was 3500 individual plants per 667 m², showing more tubers per plant, higher ratio of medium-large size tubers, highest coordination relativity between population and individual, highest yield which reached 3448.5 kg fresh tubers per 667 m².