Five dominant submerged macrophytes commonly found in Honghu Lake were collected,including Vallisneria natans (Lour.) Hara,Hydrilla verticillata (L.f.) Royle,Myriophyllum verticillatum L.,Potamogeton crispus L.and Potamogeton wrightii Morong.Their maximal quantum yields of photosystem Ⅱ(F_v/F_m) as well as rapid light curves(RLCs) were measured in situ by using pulse-amplitude modulated fluorometer(Diving-PAM).The results showed that:The measured maximal quantum yields of V.natans (Lour.) Hara,H.verticillata (L.f.) Royle,M.verticillatum L.,P.crispus L.and P.wrightii Morong were 0.603,0.723,0.751,0.778 and 0.646,respectively.All the five species’s F_v′/F_m′ from high to low order as P.crispus L.＞M.verticillatum L.＞H.verticillata (L.f.) Royle＞P.wrightii Morong＞V.natans (Lour.) Hara.In addition,there was nosignificant difference between H.verticillata (L.f.) Royle and M.verticillatum L.,all other species display statistically significant differences;All the five species’s α from high to low order as P.crispus L.＞H.verticillata (L.f.) Royle＞M.verticillatum L.＞P.wrightii Morong＞V.natans (Lour.) Hara.In addition,there was nosignificant difference between H.verticillata (L.f.) Royle and M.verticillatum L.,while all other species display statistically significant differences.All the five species’s rETR_m from high to low order as P.crispus L.＞M.verticillatum L.＞H.verticillata (L.f.) Royle＞P.wrightii Morong＞V.natans (Lour.) Hara,and all the five species display statistically significant differences;All the five species’s E_k from high to low as M.verticillatum L.＞P.crispus L.＞H.verticillata (L.f.) Royle＞V.natans (Lour.) Hara＞P.wrightii Morong.In addition,there was nosignificant difference between P.crispus L.and M.verticillatum L.,all other species display statistically significant differences.Studies have shown that P.crispus L.and M.verticillatum L.have higher light resistance capacity as well as faster photosynthetic rate,and V.natans (Lour.) Hara has lower light resistance capacity among the five dominant submerged macrophytes commonly in Honghu Lake.