Network Coding - This paper introduces a method to improve the transmission model of BigNum network coding. The main contents include the research status of network coding, the principle of BigNum network coding, the security problems existing in the existing technology, the new coding matrix proposed for the problem, the beneficial effect of the new matrix and comparison. In this paper, to improve the security of BigNum network coding, we propose two new coding matrix forms: random number matrix and Fibonacci generation matrix. We also give a proof of the invertibility of Fibonacci generate matrix.