The complex intrinsic defects of four ternary diamond-like ABX₂ (A: Cu/Ag; B: In; X: Te/Se) compounds are studied by first-principles calculations. The results show that Cu-based compounds are likely to generate acceptor V_A defect with p-type, while Ag-based compounds form donor B_A with n-type. The reasons are analyzed by the newly introduced density of energy (DOE).