Relay selection and random linear network coding are widely used and can improve the performance of wireless networks significantly. In this paper, random linear network coding which pre-forwards coding coefficients in cooperative communication system is proposed. Single relay selection and multiple relay selection are proposed for the relay selection schemes, which avoid collision problem in relay networks. Moreover, we consider channel correlation between coding coefficient and coded packet for practical environment since they are transmitted separately. We investigate the outage probability and diversity order for random linear network coding with two relay selection schemes.