The smelting method for casting copper alloy is characterized in that: 1) clean the crucible, prepare various tools for smelting operation, and clean up; 2) weigh the pre prepared refining modification refiner according to the need of treating liquid copper, put it into the oven, bake it at 200 ― 300 ℃ for 4 ― 6 hours, and reserve; 3) charge the furnace for melting: first, load the charcoal, and the refining modification refiner is prepared according to the requirement of treating liquid copper When the temperature of liquid copper reaches 1200 ℃, then add 0.8% niobium, 3.5% phosphor copper alloy and 1% rare earth, which account for the total mass of the above materials, After the temperature of molten copper reaches 1200 ℃, add the dry refining modifier for 15-25 minutes; 4) add 0.5% niobium, 3% phosphor copper alloy and 0.6% rare earth, which account for the total mass of step 3); after 20 minutes of quiescence, cast rapidly at 1165 ℃; about 3-4 minutes; 5) quiesce for 5-10 minutes, check the fracture surface and remove slag after passing the test.