The atmospheric coherence length is a very important parameter of atmospheric propagation and adaptive optics. The principle of atmospheric coherence length measurement via differential image motion measure (DIMM) angle-of-arrival fluctuation of optical wave and the measurement method dealing with the irradiance scintillation of laser propagation are introduced. The atmospheric coherence length along level propagation path is measured via differential image motion measure angle-of-arrival fluctuation of optical wave. In addition, the measurement systems dealing with the irradiance scintillation of laser propagation are used to check the results of the atmospheric coherence length measurement, and its time variation is similar, but they can be much different from each other under other conditions. Last, various errors caused by instrument are analyzed and discussed.