勞工保險為台灣第一個實行的社會保險制度，隨著高齡化的時代來臨，老年年金之支出也越來越龐大， 若要維持勞工保險制度的運作， 就必須使勞工保險基金擁有穩健的財務狀況。國內外許多學者皆認定資產配置為影響基金績效最重要的因素。 本文以1991年-2010年共20年期間，分為三年期、五年期、十年期、十二年期、十五年期以及二十年期共六種期間，投資工具為九項國內外資產，而本研究運用馬可維茲(Markowitz)的平均數-變異數(Mean-Variance)模型，研究不同期間之最適資產配置，為求取相同報酬率之下最小風險之投資組合以及效率前緣。 研究發現，最小風險投資組合的資產配置比例幾乎著重於固定收益，因為固定收益資產的標準差皆較權益證券來得低。而隨著研究期間的越長，固定收益的報酬率越高，因為早期的利率較高；而權益證券則因為容易受到外在的環境影響，導致即使投資期間拉長，報酬率也無法隨之增加。 Labor Insurance program is the first compulsory social insurance program in Taiwan. The fast aging population has caused increasing spending on old-age pension benefits in the last decade. In order to maintain a continuous operation, the program must first establish a stable financial system. “Asset Allocation” has been the most important determinants of the portfolio performance identified by many scholars. Using the Mean-Variance Model of Markowitz, this study consists of six periods, from1991-2010; separated by three years、five years、ten years、twelve years、fifteen years and twenty years, with nine different investment tools to discuss the optimal asset allocation in different periods. The study shows that in the least risky investment portfolio, percentage of fixed income (bonds/commercial bills) is higher than the percentage in stock equity because variance of fixed income is always smaller than stock equity. This study also finds that the longer the period time, the higher the return on investment in fixed income. This result is due to the fact that interest rates were higher in earlier years. On the other hand, return on investment in stock equity will not be affected by the length of period time, as it can be easily affected by other environmental factors.