Abstract: In order to investigate the response of organic matter and nitrogen removal efficiency of wetlands and characteristics of reed root exudates to different harvest time in the subtropical region, a two-year experiment (the first year from July 2017 to March 2018, and the second year from August 2018 to April 2019) was carried out in horizontal subsurface constructed reed wetlands at four different reed harvest time: W1 (un-harvest), W2 (harvest before wilting), W3 (harvest at mid-wilting), and W4 (harvest at late wilting), and the composition and characteristics of reed (Phragmites australis) root exudates and TOC concentration in wetlands was monitored. The results showed that: (1) Wetland TOC removal efficiency decreased when reeds were harvested before wilting, and increased when harvest at late wilting stage in the two experimental years. (2) The number of alkanes in the reed root exudates was the highest, the root exudates decreased after the reeds were harvested, and the results were similar in the two experimental years. (3) The relative content of alkanes in reed root exudates was the highest in the year with higher influent TN concentration, and increased after the reeds were harvested; In the year with lower influent TN concentration, the relative content of acids in root exudates was the highest, it increased under harvest before wilting and in mid-wilting treatments, but decreased under harvest at late wilting treatment. (4) The wetland TOC and TN removal efficiency were positively correlated with content of alkanes, and alkanes were the main factor in the year with higher influent TN concentration; In the year with lower influent TN concentration, acid content was the main influence factor, which negatively correlated with the wetland TOC and TN removal efficiency. The results indicated that the composition and characteristics of reed root exudates were related to the pollutant removal efficiency in reed wetlands, and reeds harvested at late wilting stage could increase the wetland organic removal.