Mechanical property prediction methods for composites are very important as theoretical tools for engineeringstructural design. To more accurately capture the transverse mechanical properties of composites, a multiscale analysismethod is developed in this paper. The multiscale analysis method includes three scales: (1) At the microscale, a microscopiccohesive model based on atomic potential energy is established for the interface; (2) At the mesoscale, a unit cell model isestablished for the fibre, matrix and interface; and (3) At the macroscale, the homogenization method, failure criteria anddamage degradation models are used for predicting the transverse mechanical properties. Subsequently, the transversemechanical properties and the damage evolution process are simulated with the multiscale analysis method. A comparisonbetween the simulations and experiments shows that the maximum error of the predicted transverse modulus and transversestrength is -4.45 % and -12.05 %, respectively. Finally, the effects of the interfacial strength on the macroscopic transversemechanical properties and the damage onset are analysed. The following conclusions are drawn from the simulation results:(1) The interfacial strength has a more significant effect on the transverse strength and ultimate strain than on the transversemodulus; (2) Decreasing the interfacial strength has a greater effect on the transverse modulus, strength and ultimate strainthan increasing the interfacial strength; and (3) The interfacial strength can change the damage onset.