This work is concerned with MHD Casson nanofluid flow in a vertical porous space with heat and mass transfer in the presence of chemical reaction. The governing non-linear partial differential equations are reduced to ordinary differential equation by employing the similarity transformations then it solved by homotopy analysis method (HAM). The results are presented with the help of graphs for different values of the involved parameters and discussed. It is found that increasing Brownian motion parameter, thermophoresis parameter and Prandtl number are lead to promote fluid temperature significantly than other parameters. Also, it is observed that increasing Lewis number lead to enhance the concentration field whereas the opposite trend can be noticed with increasing thermal parameters. Further, we have compared HAM solution with the numerical solution by using ND solver in Mathematica.