6 months baby urine smell big may be due to too little milk, diaper change is not timely and so on the situation caused, but also can not rule out the emergence of phenylketonuria this kind of situation. 1. too little milk: if the 6-month-old baby too little milk, the body will appear in the water shortage, may make the urine concentrated, easier to cause the 6-month-old baby urine smell. 2. diaper change is not timely: if the 6-month-old baby after urination, parents did not clean up in time, may be with the evaporation of urine, so that the baby appeared to the symptoms of urine smell. 3. phenylketonuria: baby if suffering from phenylketonuria, this time the body’s amino acid metabolism will have abnormal phenomenon, metabolites with rat smell, through the urine discharge, may lead to 6 months baby urine smell big situation. 6 months baby urine odor may also have other causes, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.