Abstract: Amphibian are declining worldwide, and it is an urgent task to accurately and rapidly assess the population size of amphibian through monitoring program. This study employed an estimation method to assess the breeding population size of amphibian, which includes surveys at breeding sites and PIT (passive integrated transponder) mark-recapture method. This method provides accurate population size based on short-term mark-recapture data and capture-mark-recapture model for that open populations. The method also offers several advantages:surveys at breeding sites overcome the difficulty that individual distribution is not concentrated at non-breeding seasons. Also, it can avoid the fluctuation of population size in different seasons. Based on the superiority of PIT marker in individual identification, the population size of amphibians can be evaluated quickly and accurately by several times recapture. This model was applied to a five-day capture-mark-recapture data set of toad (Bufo gargarizans) in Laohegou Nature Reserve of Pingwu County, Sichuan Province, and the population size was estimated. This method provides a simple and effective method for amphibian population monitoring, which is of great value to the assessment of rare species.