中文摘要：

众所周知,Vasicek短期利率模型,由于可取负的利率,使得利率衍生物定价计算具有不稳定现象,并引起业界对它的定价的可信度产生怀疑.该文指出只需以息票作为新的计价单位（Benchmark）,利率衍生物定价计算不稳定现象就可避免,为了说明定价的可行性,将在随机利率条件下以欧式看涨期权为例,通过数值方法对Vasicek和CIR这两类利率模型衍生物定价的误差进行分析.

英文摘要：

It is well known that the numerical method for pricing derivatives would become unstable when a positive probability for negative interest rate comes into being in Vasicek model. Thus the industry doubts the credibility of the pricing for Vasicek model. This paper indicates that the unstable phenomena could be avoided if coupon was applied as Benchmark. In order to illustrate the feasibility of pricing, we take European call-option under stochastic interest for example and analyze the deviation between Vasicek and CIR models by numerical method.