The macrozoobenthos community plays an important role in material cycling and energy flow in riverine ecosystems. During the period of March 2009 to March 2010, an investigation was conducted on the life cycle, production dynamics and trophic relationships of the dominant mayfly species in first-order to fourth-order rivers-a continuum of Shenglihe Stream in the upper reaches of the Bahe River, a main branch of the Yangtze River. According to the diversity of micro-habitats, from the upper to the lower reaches of Shenglihe Stream, 12 types of habitats were chosen for quantitative sample collection. At each station, two samples were taken with a 250 μm, D-frame kick net or a Surber net, and the samples were sieved with a 250 μm net and sorted in a porcelain dish without magnification. The specimens were kept in 10% formalin for later processing. The life cycles of the three dominant mayflies, Heptagenia sp., Isonychia sp., Ephemera rufomaculata Zhou & Zheng, 2003, were analyzed by their monthly size-class frequency distribution and their cohort and annual production were estimated by the size-frequency method. The results showed that Heptagenia sp. and Isonychia sp. appeared to develop in 3 generations per year, while E. rufomaculata had 2 generations a year. Their standing stocks exhibited a rough trend of increase from the first- to third-order rivers, then a little decrease in the fourth-order river. The estimated mean annual production of Heptagenia sp. was 200.13 g·m^-2·a^-1 and the mean annual P/B was 23.69; those of Isonychia sp. were 82.06 g·m^-2·a^-1 and 18.12; while those of E. rufomaculata were 12.30 g·m^-2·a^-1 and 8.78, respectively. Production dynamics of the three mayflies were in rough agreement with those of their biomasses, but differed significantly from each other. The daily production rate of Heptagenia sp. reached its peak (363.56 mg·m^-2·d^-1 ) in the second-order river in March, 2009, that of Isonychia sp. had its maximum value of 282.76 mg/m²·d in the third-order river in March, 2010, while the maximal daily production rate (33.36 mg·m^-2·d^-1) of E. rufomaculata appeared in the first-order river in March, 2009. By analyzing their foregut contents, the proportions of six type of diet (amorphous detritus, animal materials, vascular plant detritus, filamentous algae and diatoms) for Heptagenia sp. were 74.37%, 4.19%, 17.11%, 4.29%, 0.04%, respectively, and the contribution rates to the secondary production were 77.15%, 11.27%, 6.57%, 4.95%, 0.04%; for Isonychia sp., the proportions of its diets were 65.64%, 6.17%, 23.04%, 0.54%, 4.53%, 0.09%, respectively, and their contribution rates were 68.16%, 16.61%, 8.86%, 1.03%, 5.23% and 0.10%; while for E. rufomaculata, the proportions were 41.14%, 5.96%, 38.04%, 1.34%, 11.21%, 2.31%, respectively, and their contribution rates were 46.67%, 17.52%, 15.98%, 2.81%, 14.13% and 2.91%. The above results were different to some extent from our previous reports in Hezhuchong Stream, a second-order river of Hangjiang River and in Tanqigou Stream, a second-order river in upper reach of Changjiang River. The probable reasons resulted from the different environments and distribution regions.