The invention relates to a device and method for measuring the drifting ratio of an evaporative cooling apparatus using sector multilayer filter paper. The device is composed of two sector structures which are arranged at opposite angles, and the center of a diagonal and the center of a circle of a wind cylinder coincide during measurement. Each sector structure is composed of a plurality of stainless steel frames which are continuously connected in order, and the stainless steel frames are connected together through stay cables. Each stainless steel frame has a three-layer structure, each layer is provided with a stainless steel case, stainless steel loops and filter paper, wherein the filter paper is clamped by the stainless steel loops, spacing sleeves are used for separating the stainless steel cases in layers, and then the stainless steel cases are fixed through connecting bolts to form a stainless steel frame. Compared with the prior are, the device has a continuous structure, nonlinear distribution, in the radius of a wind cylinder, of the drifting ratio of an evaporative cooling apparatus and approximate substitution can be avoided, upper filter paper can block second drifting, middle filter paper can prevent moisture increase, so experimental data is easy to process, and an result is reliable.