[Objective] To reveal characteristics of the flood events occurred in historical period

scientifically predict the occurrence of flood and reduce the loss caused by flood disasters.[Methods] According to the analysis of grain size for 106 samples from the floodplain deposition of Shuiliu village in the northern suburbs of Xi'an City

the flood events of Weihe river in Xi'an City over the past 230 years was studied.[Results] The section studied was 5 m in thickness and consisted of silt particles

clay sand

middle size sand and coarse sand

which changed distinctly in the stratigraphic section and indicated the flood events very well. Particle size and particle parameters indicated that 21 deposit layers can be determined and at least 21 stages of floods in the section studied in past 230 years. The flood scale of these 21 flood phases were:18 th >17 th >15 th >16 th

19 th >21 th >4 th

5 th >3 rd >1 st

2 nd >6 th

7 th >10 th >11 th >8 th

9 th >13 th

14 th >12 th >20 th. The flood level over the sediment of the floodplain was bigger than 2 m when these 21 flood stages occurred except the 20 th.[Conclusion] The distribution and grain size of flood deposit layers indicated that the occurring reason for the major flood of 3 rd

5 th

7 th and 8 th flood was due to the increase in annual mean precipitation

the rest flood events were due to the increase in annual mean precipitation or concentrated precipitation in a year.