Abstract: In order to study the effects of planting density on dry matter production of purple sweetpotato under intercropping pattern of maize and sweetpotato in hilly area of Sichuan province, purple sweet potato variety ‘Nanzishu 008’ was used as test material, five transplanting densities were set to examine the leaf area index, crop growth rate, leaf area duration, dry matter accumulation, yield, yield composition and other index of purple sweet potato. The results showed that: under the condition of intercropping pattern of maize and sweetpotato, in the range of 30000-50000 plant/hm², the leaf area index increase with the increase of transplanting density while the population growth rate, population photosynthesis potential, commodity rate, dry matter ratio, fresh root yield, root starch yield of purple sweet potato all increased firstly, then decreased. Meanwhile, with the increase of transplanting density, the root number per plant, root fresh weight per plant of purple sweet potato decreased. The accumulation of population dry matter and T/R were different among transplanting densities. When the planting density was from 3.5×10⁴ plant/hm² to 4.0×10⁴ plant/hm², the dry matter accumulation, fresh root yield, starch yield and commodity rate were higher. The highest fresh root yield was 11816.9 kg/hm², which was 42.6%-53.1% of the fresh root yield under the condition of sole cropping. Therefore, under the condition of intercropping pattern of maize and sweetpotato, the suitable transplanting density of purple sweet potato variety ‘Nanzishu 008’ was from 3.5×10⁴ plant/hm² to 4.0×10⁴ plant/hm² in hilly area of central Sichuan Basin.