A carbonitriding method for thin-walled steel parts comprises the steps of carbonitriding, quenching and tempering. Specifically, as for the step of carbonitriding, adopted atmosphere includes propane, methyl alcohol and ammonia gas, the adopted carbonitriding carbon potential is 1.06+/-0.03%, the adopted carbonitriding temperature is 870+/-5 DEG C, and the adopted carbonitriding time is 300+/-5 min. By means of the carbonitriding method for the thin-walled steel parts, the performance of the thin-walled steel parts can be improved, and the process cost is reduced.