In this paper, low-velocity impact characteristics and residual tensile strength of carbon fiber composite lattice core sandwich structures are investigated experimentally and numerically. Low-velocity impact tests and residual tensile strength tests are simulated by the FE (finite element) software, ABAQUS/Explicit and its subroutine (VUMAT). In order to give more detailed description about the impact damage of the structure and improve modeling accuracy, multi-steps analysis method is employed to simulate impact process and residual tensile strength test in one analysis model. The calculation results computed by the FE model have been compared to the value of experiments, the difference of impact process simulation is about 3.3% and that of tensile strength test simulation is about 12.9%. The calculation error of computation model is acceptable, since unavoidable damage could be introduced in the courses of manufacture, processing and transportation of composite materials, and these damages are determinated difficultly in the computation programs. Next, the degradation tendency chart of residual tensile strength and impact energy threshold Uo of carbon fiber composite lattice core sandwich structures are obtained by the computation value of residual tensile strength after impacted with different impact energy. Previously, this threshold can only be obtained by experiment tests. After the contact force which is bigger than the threshold Uo impact on the sandwich structures, the residual tensile strength of structures are degraded greatly. This conclusion is significant for the design and application of carbon fiber composite lattice core sandwich structures.