The invention discloses a multi-split air conditioner system. When the temperature of an indoor environment reaches the preset temperature, the multi-split air conditioner system is controlled through a controller of the multi-split air conditioner system to run in a standby-ready mode, a refrigerant circulates between a compressor and an air and liquid separator, the capacity output of the compressor is controlled, and the pressure of a refrigerant outlet of the compressor is maintained within certain range, so when the multi-split air conditioner system is restarted to generate heat, the phenomenon of raising the lower pressure of the refrigerant to the working pressure is avoided, the cold air prevention time of an indoor unit is shortened, and the better user experience can be obtained. In addition, by setting the time of the multi-split air conditioner system entering the standby-ready mode through the controller, when the time of entering the standby-ready mode reaches the preset value, the multi-split air conditioner system is controlled to enter the standby mode, and the compressor is closed, so as to save the electric energy. The invention also provides a quick-starting heat generation method suitable for the multi-split air conditioner system.