<p>In order to understand the differences of raindrop size distribution (DSD) in complex mountainous terrain, the characteristics of DSD were analyzed by using the six-months observation data at the southern slopes, northern slopes and inside in Qilian Mountains. For all rainfall events, the number concentration of small and large raindrops on the inside and south slope are greater than that on the north slope, but midsize raindrops are less. The DSD spectrum of inside mountains are more variable and significantly differ from the north slopes. The differences in normalized intercept parameters of DSD for stratiform and convective rainfall are 8.3 % and 10.4 %, respectively, and mass-weighted diameters are 10.0 % and 23.4 %, respectively, which the standard deviation of DSD parameters on inside stations are larger. The differences in coefficient and exponent of Z-R relationship are 2.5 % and 10.7 %, respectively, with an increasing value of coefficient from the south slope to the north slope in stratiform rainfall but opposite to convective rainfall. In addition, the DSD characteristics and Z-R relationships are more similar at the ipsilateral stations and have smaller differences between the south slope and inside mountains.</p>