A numerical simulation model of falling film and droplet absorption over and between horizontal tubes in absorber is established with consideration of droplet formation and falling process. The solution temperature and concentration distribution, steam absorption rate along the pipes and between the tube bundles are analyzed. The effect of space between tubes on the coupled heat and mass transfer characteristics is made. The results show that the absorption rate due to droplet formation and falling can be up to 30%. The comparison between the calculated and experimental results shows that the numerical simulation is reasonable.