ObjectiveTo determine the optimal pool size and pooled sample size for testing whether an infection rate has exceeded the critical level of malaria epidemics using the pool sampling method and fixed sample size approach. MethodsThe function between the pooled sample size and pool size was deduced by using arcsin transformation and normal distribution approximation while controlling the probability of type Ⅰ and type Ⅱ errors. Computer simulation was used to evaluate the approximate power function. ResultsThe optimum pool size and the pooled sample size were obtained for different critical and normal levels of infection rates. ConclusionThe optimal pool size and the pooled sample size are in an inverse relationship for given probability of type Ⅰ and type Ⅱ errors, so in practice we should make an evaluation according to the sampling cost and test cost.