Abstract: The studies on Physiological characteristics of photosynthetic of Polygonum cuspidatum sieb.et zucc selected for ornamental culture were measured with the Licor-6400 portable photosynthetic system. The results showed that: (1) The light compensate point (LCP) of Polygonum cuspidatum was 64μmol/(m2·s) to 75μmol/(m2·s), and the light saturate point (LSP) was 390μmol/(m2·s) to 600μmol/(m2·s), and the apparent quantum efficiency between 0.0272 and 0.0387, these showed that the Polygonum cuspidatum had the weaker utilization efficiency on weak light. (2) The CO2 compensate concentration of photosynthesis was 105μmol/mol to 120μmol/mol, and the CO2 saturate concentration of photosynthesis was 930μmol/mol to 1051μmol/mol, the carboxylation efficiency was between 0.0365 and 0.0459. (3) The results showed that daily variation of net photosynthetic rate in leaves presented a single peak curve, and the peak value of the net photosynthetic rate was 15.0±1.8μmol/(m2·s), occurred about at 9:00. Among the five test materials, the results showed that the photosynthetic characteristics was the strongest for the tissue-cultured plantlets cultivation in the land, and the Guizhou Kaili’s was the worst.