Based on the previous study on turbulent structure, field experiments on fluctuation velocity were carried out in section Huanglingmiao of main stream of Yangtze River with a 3-D Doppler velocimeter. And a number of data such as velocity of different discharge and different vertical line were obtained. According to the field experiment data, period, frequency, period function and probability density function of large-scale coherent structure in natural river were prescribed by means of quantitative analysis. And the problem about distribution of time average velocity, turbulent intensity and Reynolds stress along depth were further analyzed and calculated. The results in this paper will deepen the understand of large-scale turbulent structure in natural river and so make the base for applying“turbulence theory” to water conservancy, hydroelectric, environment engineering and so on. Based on the previous study on turbulent structure, field experiments on fluctuation velocity were carried out in section Huanglingmiao of main stream of Yangtze River with a 3-D Doppler velocimeter. And a number of data such as velocity of different discharge and different vertical line were According to the field experiment data, period, frequency, period function and probability density function of large-scale coherent structure in natural river were prescribed by means of quantitative analysis. And the problem about distribution of time average velocity, turbulent intensity and Reynolds stress along depth were further analyzed and calculated. The results in this paper will deepen the understand of large-scale turbulent structure in natural river and so make the base for applying “turbulence theory” to water conservancy, hydroelectric, environment engineering and so on.