Based on the orbital angular momentum spectrum theory,the power expression of orbital angular momentum states of partially coherent Laguerre-Gaussian beams is derived.The effects of coherent length and beam width on orbital angular momentum are analyzed.The orbital angular momentum characteristics of partially coherent Laguerre-Gaussian beams in weak turbulent atmosphere are discussed.The results show that the relative power of the initial orbital angular momentum state of the partially coherent Laguerre-Gaussian beam does not change with the change of the beam waist radius,in terms of invariant the ratio of the coherent length to the beam waist radius.In the partially coherent Laguerre-Gaussian beam initial coherence length and radius values of the same size,with the increase of the waist radius,initial orbital angular momentum states at 1km relative power decreasing of beam propagation in weak turbulent atmosphere.