Agricultural insurance is one of the most important mechanisms to providing security for investment in agricultural and natural damage reduction. One of the modern types of insurance is weather index- based insurance that developed based on climatic parameters such as rainfall and temperature. The purpose of this study is to identifying the factors affecting wheat farmer's participation on proposed weather index-based insurance and their willing to pay the risk premium for wheat in Ahar County. The required data was collected for 289 farmers in Ahar County in 1390. Results of estimated logit model showed that the satisfactory from performance of agricultural products insurance, familiarity with weather index insurance, high school education have direct and significant effects on probability of adoption the weather index insurance , and the proposed amount of premium and the number of occurred damage in recent 3 years have reverse and significant effects on its. In this context, the level of wheat cultivators knowing about weather index insurance has the most effect on probability of adoption of weather index insurance. Based on the estimated parameters of logit model, the average premium that the Ahar wheat cultivators willing to pay was calculated and it is 91470 Rials per hectare and in comparison with the current insurance premium of wheat yield insurance, which is about 145000 Rials is reasonable. Results of the estimation of tobit model indicates that the farmer's age, education and being familiar with the weather index insurance have positive and significant effects on the willing to pay the risk premium.