Two kinds of common measuring methods of water turbidity, scattering method and transmission method are introduced from principles, characteristics and application situations. Then a synthesis detection method-ratio method, suitable for measurement of water turbidity changing in a large range is put forward based on characteristics of scattering and transmission method. Tenging TTS turbidimeter on the basis of ratio method and self-made experiment platform are used to measure the turbidity of Formazine standard solution of different turbidity values. The measured data of Tenging TTS turbidimeter and the self-made experiment platform are listed, the data-processing formulas are deduced and the turbidity values with different methods are calculated. Results indicate that with the ratio method, the measurement accuracy of water turbidity can be improved effectively and measurement range is also extended.