An important factor that affects the daily investment decision is the risk. This paper introduced the risk concept into the online leasing problem , built the risk2reward model and analyzed the online leasing problem with interest and without interest in this risk2reward model . Traditional competitive analysis reflects the relative perfor2 mance of online algorithm to benchmark algorithm (usually the offline optimal algorithm) . But this approach is too inflexible and neglects some useful information the online player may have. Different from this method , the investor can control his own undertaken risk and choose the optimal online leasing strategy according to his own risk tolerance and forecast in the risk2reward model .