Effect of both substrate temperature and ambient pressure on a flattening behavior of thermal sprayed particles was systematically investigated. In the flattening of the sprayed particles onto the flat substrate surface, critical conditions were recognized both in the substrate temperature and the ambient pressure. That is, the flattening behavior changed transitionally on the critical temperature and pressure range, respectively. A transition temperature, Tt, and a transition pressure, Pt, for those critical conditions were defined and introduced, respectively. Equivalence in the dependence both of transition temperature and transition pressure on the sprayed material's order indicated that the wetting of the substrate by the molten particle is a common domination in the flattening. Three dimensional transition map by combining both transition behavior in the flattening was proposed as a controlling principle for the thermal spray process.