Abstract- Mixed convection flow of a water-copper nanofluid in a channel under magnetic field effects has been numerically investigated. The fluid flow and temperature fields as well as the heat transfer rate have been determined by solving the Navier-Stocks and energy equations. In this study, the effects of various parameters such as the Richardson number, the Hartmann number, the solid volume fraction and the channel angle on the thermal performance of the channel have been examined. The results showed that at high Richardson numbers, the heat transfer rate decreased as the Hartman number increased. It was also found that the heat transfer rate increased as the Richardson number, the solid volume fraction and the channel angle increased. The maximum flow reversal was observed to occur in a vertical channel.