Digital fountain codes are a kind of rateless codes. Compared to the traditional block codes with fixed rate, digital fountain codes are able to adapt the changes in the channel well and can effectively avoid ″storm feedback″ in the transmission of big data. Because of the unfixed rate, the transmission protocols of digital fountain codes have a sharp difference with those of the block codes. The paper introduces several existing fountain codes based transmission protocols, based on which a new type of transmission protocol is proposed. The protocal takes a special frame structure as the basic transmission unit, which greatly reduces the effect of delay on the system performance. At last, the performance of the proposed protocol is analyzed and the influence of the parameters on the performance of the protocol is studied.