Abstract: This paper lays a foundation in the investigation into the characteristics of Ga₂O₃ containing slag.The isomelting-point contour of the ternary system of CaO-SiO₂-Ga₂O₃ was measured.The phase analysis has not been carried out in the test since our purpose is to provide a temperature dependent melting range for future research rather than draw a phase diagram of the system.In the design of the test,minimum testing points were used in an attempt to get more information and reduce some variables to simplify the mathematical processing by taking advantage of the characteristics of the ternary system coordinate and the principle of thermodynamics.