The problem of buyer-seller negotiation is extensive, which occurs not only during the negotiation period itself (the gaming problem), but also at the pre and post negotiation phases (the knowledge elicitation and commitment problems respectively). This paper focuses on the part of pre-negotiation phase and proposes a hybrid case-based approach (including CBR, ANN and PSO) in order to effectively elicit user’s negotiation preference and strategy for preparing the formal bargaining period. Based on the proposed CBR approach, past negotiation experiences are sufficiently recorded and effectively stored in the case database; similar previous cases are precisely retrieved and their solutions are adapted to suit the new negotiation problem. The proposed approach for retrieving negotiation knowledge in the pre-negotiation phase can share of past experience and knowledge, provide a fast but reasonable solution, and avoid unnecessary mistakes.