Financial derivatives provides landmark contributions for financial market, and also the unexpected market risks. For evaluating the risks more scientifically to prevent them effectively, the case-based reasoning method is introduced into the risk evaluation of financial derivatives, which arised from the domain of artificial intelligence newly. According to the analysis on various risks, combining with the principle of case-based reasoning, techniques are studied such as knowledge representation of derivative risk cases, establishment of database, retrieval of similar cases, case learning, etc. An example is used to illustrate the evaluation process, the method indicates its application validity to the field and improves the evaluation efficiency of derivative risks.