Abstract: The moving particle semi-implicit (MPS) method, which is a particle method without grid meshes, is a full Lagrangian method for incompressible flows. It has advantages in describing fluid interface with large deformation and phase transition problems. However, when the Laplace model of MPS method is applied to solve the energy equation, there will be an inaccurate solution. In this paper, a particle-grid hybrid method was proposed based on MPS method. The momentum conservation equation was solved by MPS method and the energy conservation equation was solved by finite volume method (FVM) in the calculation so that the convective heat transfer problems could be solved by the particle-grid hybrid method. It is proved that the particle-grid hybrid method is effective and has high precision to solve the one-dimensional heat conduction problem. The particle-grid hybrid method was used to simulate the natural convection in the cavity. The results show that the coupling method based on MPS method and FVM can be used to solve the convective heat transfer problem.