I agree with sheetal. If she have cough or cold..then also due to phlegm accumulation..kids will vomit. same if they have gastric issue..

little vomiting is ok. maybe she doesn't like the taste of certain food. or maybe u r overfeeding her. or it can be due some food allergies. try to eliminate food items which u think might be causing this and see what suits her. try not to overfeed.