木材由若干早晚材交替组成，为根据早晚材占比，预测试件力学性能强度，建立了以早、晚材为基本模型单元的复合材料模型。从木材细观层面出发，将木材视为由早、晚材两种不同力学性质的材料理想粘接的复合材料，以云南松为研究对象，分别获取早材与晚材各自力学参数，根据复合材料层合板理论，建立早晚材顺纹抗拉力学模型，并利用试验进行验证。结果表明，将木材视为早、晚材复合材并用层合板理论对其力学性能进行预测的方法可行；抗拉弹性模量和抗拉强度的理论值与试验值之间相对误差皆在10%以内，具有较高的可靠性，根据此模型，通过测量材料中晚材所占的体积分数，可计算材料的抗拉强度与弹性模量，为后续早晚材试验与早晚材相关模型的深入研究提供参考依据与理论基础。

Wood consists of a number of early and latewood alternately, in order to predict the strength of the mechanical properties of the specimen according to the proportion of early and latewood, a composite material model with early and latewood as the basic modeling unit was established. Starting from the fine level of wood, the wood is regarded as a composite material ideally bonded by two kinds of materials with different mechanical properties of early and late wood. Taking Yunnan pine as the research object, the respective mechanical parameters of early and late wood were obtained respectively, and according to the theory of composite plywood, the composite material tensile strength model of early and late wood with smooth grain was set up, and the test is utilized to verify the results. The results show that it is feasible to consider the wood as early and latewood composite material and use the laminate theory to predict its mechanical properties. The relative errors between the theoretical values of tensile elastic modulus and tensile strength and the experimental values are within 10%, which is highly reliable, and according to this model, the tensile strength and elastic modulus can be calculated through the measurement of the volume fraction of the latewood in the material, which will provide a good basis for the subsequent early and latewood tests and the further study of the early and latewood related models. This model can provide a reference basis and theoretical foundation for the in-depth study of the subsequent early and late material test and the related model of early and late material.