The invention provides an atomic absorption measuring method and measuring device. The wave length of ultraviolet rays produced by an atomizer are longer than 300 mm, a solar blind is taken as a detector, and the atomic absorption measuring device comprises a first optical assembly and a second optical assembly; the first optical assembly is arranged between a light source and the atomizer, the first optical assembly can focus light rays sent out from the light source, and then project the light rays into the atomizer; the second optical assembly is arranged between the atomizer and the detector, and the second optical assembly can enable light rays penetrating through the atomizer to be focused and then projected into the detector. Compared with the prior art, the atomic absorption measuring device provided by the invention has the advantages that stray lights in an ultraviolet region are removed, an optical splitting system of an atomic absorption spectrophotometer is omitted, peak searching operation required by a conventional atomic absorption measuring device before element detection can be omitted, and the detecting time is saved. In the measuring device provided by the invention, multi-element sequence or simultaneous measurement can be achieved more easily. In addition, the atomic absorption measuring device provided by the invention has a simple structure and can achieve miniaturization.