Abstract: Geotechnical control engineering is widely used in the treatment of debris flow disasters, and the damage degree of the engineering will have a certain impact on the functionality of the engineering. It affects the continuous exertion of benefits. This paper selects geotechnical control engineering of 18 debris flow gullies in Wenchuan area as the research objects, combined with field investigation, the damage degree of control engineering was evaluated. The system of evaluation index is generally divided into two factors: check dam factor and drainage channel factor. The secondary evaluation indexes are refined, including the damage degree of dam foundation, the damage degree of dam abutment, the damage degree of dam body, scouring degree of foundation, structural impact degree and slope thrust degree. The fuzzy comprehensive evaluation method is used to construct the judgment matrix and membership function, and the damage degree is divided into four grades: excellent, good, medium and poor. The evaluation results show that except for Banzi gully and Dengxi gully, the damage grades of other debris flow control engineering are good or excellent, and the evaluation results are consistent with the field investigation.