To comprehensively implement the UV atmospheric sounding of nadir and limb fields, the principle of simultaneously sounding of nadir and limb fields was analyzed and technical specifications were analyzed. Then a prototype of multiband UV atmospheric sounder with two fields was designed and developed. The optical system of the prototype is composed of a fore of lens, an annular lens, a relay of lens, and a narrowband filter. The central wavelengths of three working spectral ranges are 265 nm, 295 nm, and 360 nm, the bandwidth is less than 20 nm. The nadir field and the limb field are 10°, and 360°(141.8°—146.6°), respectively, the focal length is 5 mm, and the F number is 1∶3.3. Three wavebands were detected individually by switching UV narrowband filters. The total mass of the prototype is approximately 3 kg, and its volume is about Φ90 mm×300 mm. The spatial resolution and illuminance uniformity of image plane of the prototype were tested. The test result demonstrates that the static MTFs of nadir field and limb field are 0.25 and 0.22 respectively at a characteristic frequency of 38.5 lp/mm and the illuminance uniformity of image plane is 94%. Both MTFs and illuminance uniformity are better than that of design requirements. The prototype shows a smaller volume and a lighter weight, and satisfies the miniaturized and lightened requirements of spaceborne instruments.