A numerical investigation on the attempt to improving thermal performance in a rectangular channel by employing dual grooves is described in this paper. Four dual-groove configurations with different main groove depths (the ratio of the main-groove depth-to-channel hydraulic diameter d1/Dh is 0.0125, 0.025, 0.05 and 0.75) are investigated, while the single groove serves as the baseline. The flow characteristics, heat transfer characteristics, pressure loss and thermal performance are comprehensively analyzed cross all configurations under Reynolds numbers spanning from 8,000 to 16,000. The results demonstrated that the dual-groove contributes to the full development of the recirculation flow, with the vortical structure dimensions exhibiting a positive correlation with the main-groove depth. The averaged Nusselt numbers exhibit a monotonic increase with the experimental Reynolds number over the investigated range of 8000 to 16000. The dual-groove channel shows superior heat transfer performance compared to its single-groove counterpart at low Reynolds number and the advantage weakens with the increasing Reynolds number. The pressure loss in single-groove channel is the lowest. The pressure loss in the dual-groove channels is higher than that in single-groove channel. The pressure loss increases with an increase in main-groove depth, except for that in the dual-groove channel with the deepest main groove, which is only lower than that in the dual-groove channel with the second deepest main groove. The thermal performance in dual-groove channel with deepest main groove is the best at Reynolds number of 8,000 and 10,000, while the single-groove channel gives the highest thermal performance at Reynolds number of 16,000.