An experimental study was made to clarify the fundamental nature of the early stage of crystal growth period of frost formation phenomena. The effect of four dominant parameters on frost formation, namely, plate temperature, air temperature, air humidity ratio, and Reynolds number, are demonstrated through several frost formation properties such as frost height, frost deposition rate, and frost density. The thickness of the frost layer is affected primarily by the air humidity ratio, plate temperature, and air temperature, while the effect of Reynolds number is less significant. High humidity ratio, Reynolds number, and temperature difference Between the air stream and the plate all yield high mass deposition rates. Frost density depends primarily on frost surface temperature, besides the other parameters. Vapor diffusion in the frost layer during the crystal growth period was found to be insignificant.