Let W be a sum of Bernoulli random variables which satisfies local dependence and hz be a call function. This function has many applications in finance. In this article, we give bounds of Poisson approximation for E [ h z ( W ) ] by using Stein-Chen’s method. Our results improve the previous results. Finally, we apply these results to approximate the mean of percentage loss for each tranche in the collateralized debt obligation (CDO) tranche pricing.