Abstract: The axial compressive performance test of 30 short square columns strengthed with cementitious composites and carbon fibre mesh was completed, the damage process and damage pattern of the specimens were obtained, and the load-strain curves, load-relative displacement curves and ultimate load histograms of the cementitious composites and carbon fibre mesh were plotted, and the effects of the number of layers of the carbon fibre mesh, whether the strengthed layer was mixed with 05 seeds, and whether the surface of core columns was roughened on the axial compressive performance of the specimens were analysed. Based on the damage pattern obtained from the test, the damage mechanism was analysed, four basic assumptions were introduced, and the formula for calculating the axial compressive capacity of the normal section of short square columns strengthed with cementitious composites and carbon fibre mesh was proposed, and the calculated values were compared with the test values. The results show that: the composite strengthed method with cementitious composites and carbon fibre woven mesh can significantly improve the ultimate load and ductility of the specimen; the strengthed specimen mainly exhibits a longitudinal compression splitting damage pattern, the woven mesh in the corner region of the specimen pulls off transversely due to the effect of stress concentration; the ultimate load of the specimen increases as the number of layers of the woven mesh; after the strengthed layer is mixed with 20% of 05 seeds, the ultimate load of the specimen increases but the deformation performance decreases; the roughing treatment of the surface of the core column can effectively improve the ductility of the specimen, however, the roughing method using burin points disturbs the overall structure of the core column, which decreases the ultimate load of the specimen; the theoretical values obtained by using the calculation method proposed in this paper match well with the experimental results, which indicates that the formulae proposed in this paper are available for the engineering design.