Abstract: The conditions of the entry of solid particles the melt and influence factors on it were discussed. The thermodynamic condition of a solid particle entering the melt was established, which illustrated that the condition of a particle completely entering the melt spontaneously is zero contact angle and an energy barrier must be overcome even if the contact angle is less than π/2. The critical particle size, equation of work and kinetic condition needed for particles to completely enter the melt were also obtained.