Three case study areas from north, central and south Henan Province in China were selected for applying spatial grain size method to the research of distribution patterns of surface water body diversity. On the basis of summarizing and adapting the previous research methods of surface water body diversity from related references, a new method of space distribution length index (MSHDLI) was put forward. Then all the selected information was further processed to present the effects of different grain sizes, correlativity and effects of grain size between the correlation coefficient of MSHDLI, water network density (RD) and MSHDAI (modified Shannon diversity area index), and scaling relations between the three used indices and parameter, and multiple regression analysis model at a resolution of 1km×1km. Results showed that with the increase of spatial grain size, the granularity of the response curves of MSHDLI, RD and MSHDAI belonged to drop type; MSHDLI maintained significant correlativity with RD and MSHDAI with average correlation coefficient of 0.997和0.878 (P<0.01), respectively. Effect of grain size of correlation coefficient was significantly positive correlation between MSHDLI, RD and MSHDAI. The fitting function of MSHDLI and RD was logarithmic function, MSHDLI and MSHDAI was polynomial function. Multivariate linear regression model of MSHDLI, RD and MSHDAI indices was also conducted to show that MSHDLI was the dependent variable and RD, MSHDAI were the independent variables. The fitting model showed that MSHDLI and RD, MSHDAI had linear correlationship, and the level of MSHDLI to explain the others was above 95%. To a certain extent, MSHDLI can be a good combination of the indexes of RD and MSHDAI to describe the breadth and the spatial discreteness in surface water resource distributions.