An improved splice method for mid-diameter steel bars (10-16mm) used in RC structures was developed, which can make the installation more easily and economic through the hybrid connection of welding and overlapping. In order to study the mechanical behavior of welding-overlap splices, a total of 138 steel bar splice tests were conducted, including both the steel-concrete interaction group and the lonely-steel group. Through the splice tensile experiment, the failure model and ultimate strength of the improved splice was summarized. Meanwhile, the failure mechanism was analyzed by the FEM analysis. The test results show that: hybrid connection of welding and overlapping is a simpler splice method which can realized the reliable splice in the RC structures, the ultimate load of the improved splice is sufficient for the application and the failure model is reasonable. Base on the test results, some suggestions for application were given. The economic analysis of a real application case is conducted, which shows a good prospect of proposed connection.