Brief review on organic magnets will be given first. Then we propose models to describe the organic magnets. Different methods including the first-principles full-potential linearized augmented plane-wave (FPLAPW) method, the Density Matrix Renormalization Group (DMRG) and the Green’s Function Method are employed. The magnetic properties, the specific heat and the magnetic phase transition are calculated and discussed .Our theoretical results are compared with experimental data , and some novel experiments are explained.