Linear stability analysis is used for the commencement of thermosolutal convection in Jeffrey nanofluid layer with magnetic field, while the Darcy model is used for the porous medium. Brownian motion and thermophoresis are both used in the Jeffrey nanofluid layer. Furthermore, the thermal energy equations contain regular diffusion and crossdiffusion terms. The normal mode technique is used to study stationary convection. The effects of the Jeffrey parameter, solutal Rayleigh number, medium porosity, nanoparticle Rayleigh number, thermo-nanofluid Lewis number, thermosolutal Lewis number, modified diffusivity ratio, Dufour parameter, Soret parameter, and magnetic field on the system's stability have been examined. The magnetic field is discovered to stabilize the Jeffrey nanofluid layer for stationary convection, and Jeffrey parameter is found to destabilize the Jeffrey nanofluid layer for stationary convection. The effect of various parameters on thermal Darcy-Rayleigh number has been presented graphically. © 2023 by Begell House, Inc.