My 7mths old have been rejected milk. Normally she drank170ml but recently she been drink lesser, sometime 100ml to 130ml every 3.5 to 4 hourly.What should I do? Will she have not enough nutrient?

Teething is a possibility. Is ur baby on solids yet? If yes, u can consider increasing ur solids or helping her enjoy her solids so that she will intake more. It's usually just a phase, or it could be an outright way of them telling u they don't like milk anymore. Lol. My son was like that. Since 5+months, v v seldom drink more than 120 but gradually became a big solids eater. Abt 400-700ml milk ok for after 6 months...u can check kk info on weaning too https://www.kkh.com.sg/HealthPedia/Pages/FoodNutritionWeaning.aspx