確定提撥制已逐漸成為退休金制度的主流。在確定提撥制下之參與者所能獲得的退休金金額有高度不確定的風險，適當的投資策略在此制度下就顯得格外重要。本文中藉由模擬與最適化的方法，探討適合各種不同風險偏好的投資人之最適提撥率與最適投資策略，以期降低確定提撥制計畫參與者的退休金不足的風險。本文主要得到兩項結論：（一）整體投資的結果與實務上生命週期型態(Lifestyle)投資方式呈現類似的現象。（二）在加入交易成的因素後，我們發現當債券及股票收取交易成本時，原本投資在長債的部份減少，轉而投資在短債。當股票之交易成本變很高時，投資在股票的比重會些微下降，但不會有很大的影響。

A shift from defined-benefit pension plan towards defined-contribution pension plan is currently popular around the world. Under DC plan, employers transfer the pension fund investment risk to the employees. No one knows if the DC plan will he able to provide a good pension benefit when the day of retirement arrives. Therefore, it is essential for the employees to choose optimal investment strategies during the accumulation phase so that they will have sufficient funds targeted in their retirement. In order to reduce the risk of individual DC member, we investigate the methodology of finding the optimal contribution rate and asset allocation to reach a certain target of the retirement replacement rate for different risk tolerant individual in this paper. We draw two conclusions from our investigations. First, the optimal investment strategy is very similar to the "lifestyle" investment strategy. Second, we find the influence of the transaction cost in the case of equity is very limited to the strategy of asset allocation. But, the influence of the transaction cost in the case of long-term bonds is more significant. We will switch the assets held in long-term bonds to short-term bonds.