Abstract: Gelatin film with adsorbed iodine vapour is used for measuring cloud droplets.It can be used for continuous sampling of cloud droplets.The traces of droplets are clear with high contrast.The sampling quality is better than other current methods.Experimental results concerning the relation between the diameters of water droplets and those of their traces on the film,the minimum sensible droplets diameter and the critical unbroken drop diameter during high speed sampling are given.