Abstract: The relationship between the critical diameter of droplet drop and the wall wettability on the homogene- ous surface，and the drop phenomenon of droplet polymerization on the heterogeneous surface，were studied with the pseudo-potential lattice Boltzmann method ( LBM) multiphase flow model． The influence of droplet size，wall wettability，and droplet radius ratio on the polymerization and drop of droplets on the heterogeneous surface was ana- lyzed． The results show that: ( 1) The heterogeneous surface，to a certain extent，can induce droplets of corre- sponding size to polymerize and drop． In addition，the size range of the droplets can be expanded by increasing the contact angle in the middle region． ( 2) The bigger the difference of the contact angle ( Δθ) of the heterogeneous surface，the faster the droplets polymerize，and the stronger the spreading ability of the droplet on the wall surface become，the smaller the longitudinal oscillation amplitude． ( 3) Within a certain range，the larger the radius ratio of droplets，the larger the internal pressure difference between the two droplets，and the faster the two droplets polymerize，and the droplet can gain additional kinetic energy and fall off the wall surface．

Key words: heterogeneous surface, multiphase flow, droplet, lattice Boltzmann method, numerical simulation