Abstract: In order to study the electromagnetic thrust characteristics of double sided long primary linear induction motor（DSLPLIM） used in electromagnetic ejection and space experiment system, the analytical expression of air-gap magnetic density of DSLPLIM considering end-effect was deduced based on electromagnetic field theory and integral calculation of primary traveling wave current layer and secondary current. Then, in order to weaken the ripple of electromagnetic thrust, a type of full-filled winding was used to improve the sinusoidal distribution of air-gap flux density of DSLPLIM. And in order to enhance the electromagnetic thrust of DSLPLIM, a type of slotted secondary plate structure was adopted to optimize the eddy current path. Finally, the air gap flux density distribution and electromagnetic thrust characteristic curves of the DSLPLIM were calculated by using the deduced analytical formulas and 3 D finite element simulation software respectively. The comparison results show that the full-filled winding can not only weaken the electromagnetic thrust ripple, but also effectively increase the magnitude of the electromagnetic thrust, and the operational performances of the DSLPLIM are improved. And the modified secondary slotting structure can effectively enhance the electromagnetic thrust of the motor and improve the thrust density.