A new method of testing frother performance was proposed. Four parameters were tested: maximum foam volume, foam half-life, gas-liquid ratio and mean foam rise velocity. Among them the former two parameters indicate frother's foaming ability and foam stability respectively, and the latter two indicate water carrying ability and foam viscosity, respectively. The performance of four frothers in a two-phase (solution-air) system was tested and batch flotation tests on a copper ore were carried out. By analyzing frother performance in a two-phase system and comparing with the flotation results, correlation between them was found. Higher-copper concentrate grade was obtained by frothers with weak water carrying ability and low foam viscosity. And frothers with strong foaming ability and stable foam tend to obtain higher copper recovery.