RU-NC column is a new type of composite structure， which is composed of reinforced ultra-high performance concrete （RU） tube and normal concrete （NC） core column. In order to investigate the axial compression performance and the bearing capacity calculation method of RU-NC composite short columns， the axial compression test was carried out considering the experimental parameters， including wall thickness of UHPC tube， stirrup spacing and steel fiber volume fraction. While a comparative test of U-RC composite short columns composed of ultra-high performance concrete （U） tube and reinforced concrete （RC） core column reinforced with spiral stirrups was carried out. Therefore， numerical analysis was carried out based on the finite element modes established on ABAQUS software. The results show that the whole compression process of RU-NC composite short column could be divided into elastic stage， crack working stage and steel yield stage. Both RU tube and spiral stirrups have a certain constraint effect on the core concrete. The failure mode of composite column is characterized by that the RU tube and the concrete core were crushed， and the spiral stirrups were broken at the same time. Compared with U-RC composite short column， RU-NC composite short column with steel cages moving from core concrete to UHPC tube has better crack resistance， ductility and higher ultimate bearing capacity. The bearing capacity of RU-NC composite short column increases linearly with the increment of UHPC tube wall thickness and UHPC tensile strength， and shows a nonlinear trend with the decrease of stirrup spacing. The ultimate bearing capacity of RU-NC composite short column cannot be accurately calculated by using the current code and the existing literature algorithm. Based on the theoretical analysis of RU tube confined concrete， the axial compression bearing capacity algorithm of composite short column is proposed. The mean value of the ratio of the calculated value to the test results is 0.984， and the variance is 0.005 3， showing high accuracy， which can lay a foundation for the design and application of the new composite structure in the future.