A method of manufacturing a metal frame for a mobile communication terminal which comprises a housing frame forming an edge exterior of the mobile communication terminal and exposed outside and a bracket frame formed inside an edge of the housing frame to support a display panel and a main board of the mobile communication terminal, the method comprising: a first operation of forming a metal preform having a square pipe shape having a hollow square cross section and a certain length by extruding a metal material of an aluminum alloy; a second operation of forming the housing frame having a square ring shape by cutting the metal preform having the square pipe shape at regular intervals in a longitudinal direction; a third operation of forming an uneven portion for coupling with a casting by performing a first CNC process along a circumference of an inside of the housing frame having the square ring shape; a fourth operation of forming a bracket frame preform which comprises an under gate portion disposed at one side and an under overflow portion disposed at the other side by inserting the housing frame comprising an uneven portion formed on the inside into a die casting die having a shape corresponding to the bracket frame and injecting a molten metal material into the housing frame to have a structure in which the under gate portion is formed at one side of the housing frame into which a metal material for die casting is injected and the under overflow portion is formed at the other side of the housing frame from which the metal material for die casting is discharged; a fifth operation of removing the under gate portion and the under overflow portion formed at the one side and the other side of the bracket frame preform by performing a second CNC process on the bracket frame preform; a sixth operation of forming one or more component mounting holes by pressing an inner surface of the bracket frame preform from which the under gate portion and the under overflow portion are removed; a seventh operation of completing the bracket frame by performing a third CNC process on the bracket frame preform comprising the component mounting holes; and an eighth operation of coating a surface of the metal frame comprising the housing frame and the bracket frame with an anticorrosive oxide film and a color through anodizing, wherein before the housing frame being inserted into the die casting die, a preheating process is performed on the housing frame under a condition with a preheating time from 30 to 60 seconds and a preheating temperature from 200 to 250 degrees. a first operation of forming a metal preform having a square pipe shape having a hollow square cross section and a certain length by extruding a metal material of an aluminum alloy; a second operation of forming the housing frame having a square ring shape by cutting the metal preform having the square pipe shape at regular intervals in a longitudinal direction; a third operation of forming an uneven portion for coupling with a casting by performing a first CNC process along a circumference of an inside of the housing frame having the square ring shape; a fourth operation of forming a bracket frame preform which comprises an under gate portion disposed at one side and an under overflow portion disposed at the other side by inserting the housing frame comprising an uneven portion formed on the inside into a die casting die having a shape corresponding to the bracket frame and injecting a molten metal material into the housing frame to have a structure in which the under gate portion is formed at one side of the housing frame into which a metal material for die casting is injected and the under overflow portion is formed at the other side of the housing frame from which the metal material for die casting is discharged; a fifth operation of removing the under gate portion and the under overflow portion formed at the one side and the other side of the bracket frame preform by performing a second CNC process on the bracket frame preform; a sixth operation of forming one or more component mounting holes by pressing an inner surface of the bracket frame preform from which the under gate portion and the under overflow portion are removed; a seventh operation of completing the bracket frame by performing a third CNC process on the bracket frame preform comprising the component mounting holes; and an eighth operation of coating a surface of the metal frame comprising the housing frame and the bracket frame with an anticorrosive oxide film and a color through anodizing, wherein before the housing frame being inserted into the die casting die, a preheating process is performed on the housing frame under a condition with a preheating time from 30 to 60 seconds and a preheating temperature from 200 to 250 degrees.