Mature Myriophyllum spicatum L. were planted respectively in 30NTU, 60NTU and 90NTU turbid water of suspended sands. In these turbid waters, the size of suspended sands were less than 100μm. After two months, the leaves near their stems were measured by a newly developed, submersible, pulse-amplitude modulated (PAM) fluorometer. Diving-PAM. The results indicated that photosystem II of Myriophyllum spicatum didn't damaged apparently in the turbid waters by the detection of F_v/F_m and Fo. After the leaves were illuminated by actinic light of 30μmol photon/(m²·s) for 10 s, △F_v/F_m and q^P didn't decrease significantly in 30 and 60 NTU turbid waters less than those in the control water, while q^P in 90NTU turbid water was remarkably lower than that in the control water (p<0. 05 ). q^N in these turbid waters was less than 0. 1, indicating that heat dissipation of the plants was low, and more energy took part in light chemical reaction. In addition, the diurnal variational extent of rETR in turbid waters was smaller significantly than that in the control water, and photosynthesis of these plants significantly decreased with turbidity of water increasing. The diurnal variation of F_v/F_m under irradiance exhibited gentle ＂V＂ shape in the turbid water, indicating that MyriophyUum spicatum L. could endure higher irradiance. When turbidity of water was more than 60NTU, Fn/Fm of these plants restored slower than that of the control water, but their difference wasnt significant. Maximal rETR also decreased with the increasing turbidity of water, showing that photosynthesis ability of the plants decreased apparently. All above-mentioned results indicated that Myriophyllum spicatum L. , one kind of submerged macrophytes, was more tolerant to high turbid waters of suspended sands. Suspended sands didnt influence significantly photosystem and the tolerance to photoinhibitory stress, but did significantly photosynthetic ability of the plants (P<0. 05 ).