The radial stress-strain relationship of wood under monotonic and repeated compressive load was studied, according to the tests on the clear wood specimens under monotonic and repeated compressive load. The results show that the monotonic compressive stress-strain curve and the skeleton curve of repeated compressive stress-strain curve are well coincident when the strain is less than 0.16. When the strain is over 0.16, the difference between these two is gradually increased, but they can still be described by the same mathematical model. In the cyclical process, the reloading path and unloading path are expressed by linear and double fold line models, respectively. Based on the comprehensive consideration of the typical characteristics of unidirectional compression and repeated loading and unloading, the stress-strain model of wood under repeated compressive load was established. Based on the established model, a MATLAB program was then written into the MATLAB software. Good consistency was found between the predictions of the model and the test results.