The invention discloses a multi-split system and a method for judging the refrigerating capacity of indoor units of the multi-split system to be insufficient. The method includes the following steps that when the multi-split system runs, the running time of each refrigeration indoor unit in the multiple indoor units, the opening degree of a restricting element in each refrigeration indoor unit, the inlet temperature and the outlet temperature of an indoor heat exchanger in each refrigeration indoor unit and the saturation temperature corresponding to the low-pressure pressure of a dividing device are obtained; and whether the refrigerating capacity of the refrigeration indoor units is insufficient or not is judged according to the running time of each refrigeration indoor unit, the opening degree of the restricting element in each refrigeration indoor unit, the inlet temperature and the outlet temperature of the indoor heat exchanger in each refrigeration indoor unit and the saturation temperature corresponding to the low-pressure pressure of the dividing device. By means of the method, effective judgment on the refrigerating capacity of the refrigeration indoor units can be achieved, the system can correspondingly conduct corresponding adjustment according to judgment results, the requirement for comfort of rooms is met, and the user experience is improved.