A process apparatus and a mutual insurance method performed by the process apparatus are provided. The process apparatus is connected to a database storing a basic insurance group, receives a basic insurance application of an applicant, generates basic policy information of the applicant according to the basic insurance group and the basic insurance application and stores the basic policy information in the database. The process apparatus further calculates a current basic insurance premium of the applicant according to the basic policy information and a current death number corresponding to the basic insurance group. The process apparatus further transmits the current basic insurance premium to the applicant. Thereby, the process and security of the insurance are simplified and improved respectively.