The effects of solution, cold deformation and aging on the grain size, precipitate size and distribution of low concentration Cu Ni Si alloy were systematically studied by means of metallographic microscope and transmission electron microscope (TEM). The mechanical and electrical properties of the alloy were also tested. The results show that compared with the other four processes, the grain size of low concentration Cu Ni Si alloy is finer (average grain size is 25 μ m) and the distribution of precipitates is more dispersed after vertical on-line solution treatment + cold deformation + aging combined thermomechanical treatment, with tensile strength of 579 MPa, yield strength of 521 MPa, yield ratio of 0.9, elongation of 9% and conductivity of 52.2% IACS; compared with C70250 and tmg0.5 alloy, low concentration Cu Ni Si alloy has excellent comprehensive properties, good heat dissipation and reliable dimensional stability when used in high power current, which can be widely used in automobile connector and other fields as high strength and high conductivity elastic material.