Abstract: The slot-less tubular permanent magnet linear synchronous machines (STPMLSM) not only avoid the cogging force caused by the slot structure, but also solve the problem of difficult processing of the primary iron core. The thrust ripple of STPMLSM is caused by the primary iron core end effect and the asymmetric inductance of the three-phase winding, which is between the cogging structure and the air-core structure. Accurate calculation of thrust ripple is the key to the design and optimization of STPMLSM. In this paper, an accurate subdomain analytical model considering the primary end effect is established, which can quickly calculate the air-gap magnetic flux density and thrust ripple under no-load and load conditions. This model ensures the accuracy and efficiency of the calculation results. Based on this analytical model, the thrust ripple of STPMLSM at load is reduced sharply by adopting three schemes including optimizing the primary iron core length, three-phase winding position and coil turns number, and thus the thrust ripple of the prototype is reduced from 11.04% to 2.78%. Finally, the correctness of the accurate subdomain analytical model and the optimization schemes is verified by the results of finite element model and prototype experiment.