The power-split gear mechanisms is widely applied in power transmission because of the advantages of compact design, lighter weight and high power density. The load sharing and the load distribution are the important performance issues while designing the power split mechanisms. The paper propose a computerized approach based on the influence coefficient method for loaded tooth contact analysis of such the gear transmission. Not only the load sharing of the multiple contact tooth pairs and the loaded transmission errors, but also the distributed contact stresses and the corresponding contact patterns on all the engaged tooth flanks can be calculated by using the proposed LTCA approach. Some analysis results are also discussed with a study case of the first planetary stage of a compound cycloid planetary gear drive.