It is difficult to evaluate and predict the mechanical surface quality of woven ceramic matrix composites due to their anisotropic and non-homogeneous structure. The present paper proposed a new method of evaluating grinding surface quality on composites by the study on surface waviness. Using a non-contact optical measurement instrument, the method was developed on 2.5D SiO2/SiO2 composite. Three-dimensional (3D) surface characterization parameters were calculated to evaluate the surface waviness. Then the results were verified by an experiment using a contact surface profile measurement instrument. The formation mechanism of the waviness is also analysed in this paper according to knowledge on mechanical damage phenomenology. Fiber orientation plays the decisive role in grinding surface waviness of woven ceramic matrix composites, which is different from traditional waviness formation theory caused by machine tool system vibration. And we found some outstanding characteristics of the surface waviness. If the tow was perpendicular to the grinding surface, the surface waviness was properly on wave crest. while if the tow was parallel to the grinding surface, it was properly on wave trough. Based on the results obtained, grinding surface waviness of composites can be predicted, then it is expected to provide a useful guideline for optimizing the use performance such as assembling, sealing, lubricity, etc. (C) 2013 Elsevier B.V. All rights reserved.