The invention discloses a multi-split air conditioner control method and system. The actual environment temperature, the set temperature, the actual environment humidity and the set humidity of each started indoor unit are acquired; and the comfortable sensation load rate of each started indoor unit is calculated, the total comfortable sensation load is calculated, and the frequency of a compressor and the opening degrees of expansion values of the indoor units are adjusted according to the total comfortable sensation load. According to the multi-split air conditioner control method, the temperature, the humidity and the indoor unit capacity hosepower are taken into consideration, the total comfortable sensation load is worked out, the frequency of the compressor and the opening degrees of the expansion values of the indoor units are adjusted according to the total comfortable sensation load, frequent frequency fluctuation of the compressor is avoided, the comfortable sensation judgment accuracy is also improved, the comfortable sensation of the indoor units is improved, the ideal indoor unit comfortable sensation is achieved, the balance and the stability of a multi-split air conditioner are improved, the user satisfaction degree is improved, and the market competitiveness of the multi-split air conditioner is improved.