Dynamic mesh technology and UDF programming technology provided by Fluent software were used to build the numerical simulation model of the inner flow field of nozzleless booster combined with the erosion and combustion law of nozzleless booster. In order to check the precision of the numerical simulation model, two ground verification experiment of two nozzleless booster was carried out and the thrust curve and pressure curve of the engine were basically agreed with the numerical simulation result, which indicated that the accuracy was within the error range. Finally, the effects of different half angle and different charge molding on performance of nozzleless booster were studied. The results show that the performance achieves optimization when the half angle is 24 degrees. Series and layer charge type can improve the specific impulse of nozzleless booster effectively.