The high-temperature absorber is one of the largest components in the absorption heat transformer. It has a decisive effect on the overall system efficiency. Nevertheless, studies analyzing the efficiency of high-temperature absorber are incomplete and scarce. In this study, we designed an experimental apparatus similar to the conventional single-stage absorption heat transformer. The high-temperature absorber was used as the horizontal falling film with the copper floral tubes. The comprehensive heat transfer performance of the high-temperature absorber was analyzed based on its inlet condition parameters such as the film Reynolds number, strong solution concentration, hot water velocity, hot water temperature, and temperature of evaporation. The results indicate that the heat transfer performance of the high-temperature absorber was rapidly decreased after the film Reynolds number exceeded 50. Accordingly, we decided to use the film Reynolds number of 50 as an inflection point to determine the heat transfer performance in our experiment. At this point, the heat transfer rate and overall heat transfer coefficient were 4.42 ㎾ and 1,367 W/㎡K, respectively.