Submerged macrophytes are known as key communities in shallow lake ecosystem. It plays important role in water environmental quality and aquatic ecosystem structure. However, several factors such as contamination, soil erosion cause water turbidity in many shallow lake, and underwater light become largely insufficient, finally result in the death of submerged macrophytes. Therefore, researches about influence of water turbidity on growth of submerged macrophytes can offer an academic method and measurement for ecological restoration of water environment. Potamogeton cripus is a perennial submerged macrophytes usually found in freshwater lakes, ponds and canals. In this study, the seedlings of Potamogeton cripus were transplanted into the waters with different turbidities of 30, 60, 90, 120, 150 NTU and 180 NTU(Nephelometric Turbidity Units) made by suspended substance with less than 100 microns in diameter. The growth of the seedlings of Potamogeton cripus in each treatment were investigated. Meanwhile, Photosystem Ⅱ (PSⅡ) photochemical efficiency (Fv/Fm ratio), quantum yield (Yield), photochemical quenching (qP), non-photochemical quenching (qN) were also measured by a submersible, pulse-amplitude modulated (PAM) fluorometer: Diving-PAM. The method of chlorophyll fluorometer analysis was shown as an approach with simple, convenient, sensitive, real-time, undestroyed and undisturbed advantages, allowing us to diagnose photosynthesis of submerged macrophytes, and analyze responsive mechanism of submerged macrophytes instantaneously.The results showed that the seedlings of Potamogeton cripus had a big tolerance to turbid water. When the seedlings grew in the waters with 30, 60 NTU and 90 NTU, and their survival, growth and photosynthesis structure of PSII were not influenced markedly(p>0.05), indicating that the seedlings of Potamogeton cripus could adapted themselves to low turbidity stress. When water turbidity exceeded 120NTU, survival and growth of the seedlings of Potamogeton cripus were not significantly influenced at short-term (10 days) stress. However, along prolongation of experimental days (>10days), the seedlings of Potamogeton cripus could survive but growth was markedly inhibited. When the leaves of seedlings exposed to light stress suddenly, high non-photochemical quenching (qN) value detected in the study demonstrated that they could protect PSII by increasing heat dissipating. Under long-term(80days) stress, the seedlings of Potamogeton cripus in high turbidity (120，150 NTU and 180 NTU) began to die in a large scale, Fv/Fm, Yield, qP were shown to be much less than those of the control treatment (p<0.05), and rapid decrease of qN indicated that photosynthesis structure of PSII began to be destroyed.