This　paper　aims　to　predict　apparent　advancing　and　receding　angles,　i.e.,　the　angles　between　the　liquid-gas　interface　and　the　horizontal　plane,　of　droplets　on　spherical　surfaces　using　the　intrinsic　advancing　and　receding　contact　angles,　namely　the　angle　between　the　liquid-gas　interface　and　the　solid-liquid　interface.　Based　on　the　Gibbs　free　energy,　droplet　volume,　and　the　correlation　between　the　contact　angle　and　the　apparent　angle,　this　study　predicted　the　apparent　angles　of　droplets　on　spherical　surfaces　and　the　predicted　values　were　verified　by　experimental　results.　Results　show　that　intrinsic　advancing　and　receding　contact　angles　are　(91±2)°　and　(55±3)°,　respectively,　on　a　flat　PET　(Polyethylene　Terephthalate)　surface.　For　droplets　on　the　edge　of　advancing　or　receding,　the　contact　angles　equal　to　the　corresponding　intrinsic　contact　angles　when　the　Gibbs　free　energy　of　the　system　is　at　the　minimal　value,　where　the　corresponding　apparent　angles　are　apparent　advancing　and　receding　angles.　Therefore,　the　apparent　advancing　and　receding　angles　of　droplets　on　spherical　surfaces　can　be　predicted　by　minimizing　the　system　Gibbs　free　energy.　It　is　shown　that　the　measured　apparent　advancing　angles　are　(118±3)°,　(110±2)°,　(103±2)°,　and　(100±2)°,　the　apparent　receding　angles　are　(82±2)°,　(71±2)°,　(64±3)°,　and　(62±2)°,　on　spherical　surfaces　with　radius　of　curvatures　of　2　mm,　4　mm,　6　mm,　and　8　mm,　respectively.　Such　measured　results　agree　well　with　the　prediction.　In　conclusion,　this　paper　develops　a　model　that　predicts　apparent　advancing　and　receding　angles　of　droplets　on　spherical　surfaces　using　the　intrinsic　advancing　and　receding　contact　angles,　droplet　volume,　and　radius　of　curvatures　of　the　spherical　surfaces.　©　2021,　Chongqing　Wujiu　Periodicals　Press.　All　rights　reserved.