In liquid inkjet printing, a critical quality issue is coalescence between droplets on media surface. To control the coalescence processes, it is useful to study how parameters, including liquid property (density, viscosity and surface tension) and affinity between liquid and a solid surface (advancing and receding contact angle), affect to the processes. However, the effect of changes with the parameters in coalescence processes between picoliter-sized droplets is not studied minutely in previous reports.This paper describes simulation results about deriving equations of the parameters for coalescence processes between two droplets and experimental results for verification of the simulation results under the condition, in which absorption of moisture and evaporation of droplets can be neglected. In our works, experimental and simulation results are almost consistent, and some of the equations can be applied to actual coalescence processes.