Cat vomiting grass-green liquid may be caused by catching a cold, improper diet, gastrointestinal disease, or eating grass. The cat’s mental state needs to be observed. If the cat is in poor spirits, does not eat or drink, has diarrhea, or repeatedly In the case of vomiting, it is best to take the cat to the pet hospital to check the cause and then treat it. If the cat only vomits once and no other abnormalities occur, then it is fine. You can feed probiotics to regulate the intestinal tract.