The invention discloses a preparation process for a radiator good in sealing performance. The preparation process comprises the steps of preparing 
die casting aluminum 
alloy and an insert. A first annular groove is formed in the horizontal contact surface of the insert and the 
die casting aluminum 
alloy. A second annular groove is formed in the vertical contact surface of the insert and the 
die casting aluminum 
alloy. A first annular protrusion is arranged in the position, matched with the first annular groove, of the die 
casting aluminum alloy. A second annular protrusion is arranged in the position, matched with the second annular groove, of the die 
casting aluminum alloy. Preparation of the die 
casting aluminum alloy and the insert comprises the following steps of 
raw material smelting, die casting, 
machining, cleaning and packing, and cleaning and packing are conducted after 
machining is completed and the die casting aluminum alloy and the insert are qualified after being subjected to leakage testing. According to the preparation process for the radiator good in sealing performance, leakage testing is conducted under the condition of 0.2 MPa air pressure, and leakage is avoided, so that the leakage problem of a part inlaid with the insert in the aluminum alloy die casting industry is solved; the requirements for the sealing performance, the heat dissipation performance, the 
mechanical strength and other performances in the using process of the radiator can be met, the maintenance cost is reduced, the production efficiency is high, and the market competitiveness is very high.