Grain boundary character distributions (GBCDs) have been measured for both Σ13a and Σ2 coincidence site lattice (CSL) boundaries in WC-Co composites under plastic deformation condition via five parameter analysis (FPA) method. For the two CSL boundaries, compared to the cases in the undeformed sample, both populations and the habit plane occurrence frequencies of the CSL boundaries decreased in the plastic deformed sample. The interpretation about the evolution of GBCDs during plastic deformation is proposed based on the fine-sorted crystallographic plane categories.