Abstract: Response of carbon fiber composites under longitudinal compression were researched using the tool of compressive test and finite element simulation. The progressive damage during the loading process was detected with high speed camera and the final failure mode was observed by optical microscope. Based on fiber initial misalignment and matrix Drucker-Prager plastic constitutive model, finite element models were established using ABAQUS to analyze the results of different fiber initial misalignment models including shear mode and extensional mode. Results show that elastic and plastic deformations are both found during the longitudinal compression. Discrete two-dimensional fiber-matrix finite element model can efficiently simulate the process of compression, which corresponds to the test results. Compressive strength of composites depends on the fiber initial misalignment and shear yielding of plastic matrix. And it increases with the decreasing of fiber initial misalignment amplitude, increasing of fiber initial misalignment wavelength, as well as the increasing of fiber volume fraction.