To evaluate eco-hydrological functions of natural mixed forest of coniferous and broad-leaved trees, a research on the relationships among throughfall characteristics, spatial throughfall distribution patterns and rainfall in natural secondary mixed forest of Xiaolong Mountains was conducted by statistics and geostatistics. Data of 29 rainfall events with gross precipitation of 947.3 mm were collected. Total throughfall and throughfall ratio were 742.6 mm and 0.783 9, respectively. Throughfall increased with increasing rainfall, which can be well described by linear, logarithmic and Mitscherlich models. The more the rainfall amount, the higher the throughfall ratio was. Moreover, throughfall ratio increased with increasing rainfall and the relationship can be well described by logarithmic and Mitscherlich models. Variation coefficient of throughfall is negatively correlated with precipitation and the relationship can be described by Mitscherlich model. As rainfall increases, the ununiformity of spatial distribution of throughfall tended to decline and eventually approached a steady state. The spatial distributions of throughfall showed significant differences among different rainfall classes.