In this article, heat the dissipation effect of a ferrofluid on natural convection flow in an inclined cavity at the presence of an external magnetic source has been analyzed with the lattice Boltzmann method (LBM). The cavity is filled with the carrier fluid of kerosene and nanoscale ferromagnetic particle of cobalt. This study has been carried out for the pertinent parameters in the following ranges: the Rayleigh number of carrier fluid, Ra = 10 3-105, the volumetric fraction of nanoscale ferromagnetic particle between 0 and 4%, and inclined angles (θ = 0°, 30°, 60°, 90°, and 120°) is the size of the nanoscale ferromagnetic particle is fixed at 45 nm. Results show that the heat transfer decreases by the increment of the nanoscale ferromagnetic particle volume fraction for various Rayleigh numbers and inclined angles. The external magnetic source influences the nanoscale ferromagnetic particle at Ra = 104 more than other Raleigh numbers, as the least values were observed at Ra = 103. Just as the least value of heat transfer is obtained at the inclined angle of θ = 90° for multifarious Rayleigh numbers in the absence of nanoscale ferromagnetic particle of cobalt, so the least effect of the nanoscale ferromagnetic particle at Ra = 103 and 105 is perceived for it. Generally, the effective situation of heat dissipation ferrofluid is found at the inclined angle of θ = 0°among the studied inclined angles.