The invention discloses a method for judging proper amount of refrigerants for a multi-united air conditioning unit, comprising the following steps of: after adjusting a four-way reversing valve (1) of the unit to a refrigeration mode and starting and running a compressor (2) of an outdoor unit for a period of time t, measuring an outdoor environment temperature T, the frequency f of the running compressor (2) and the exhaust pressure P0 of the compressor (2); and then comparing the exhaust pressure P0 of the compressor (2) with the standard region of an exhaust pressure corresponding to the outdoor environment temperature T and the frequency f of the running compressor (2), if the exhaust pressure P0 of the compressor (2) is positioned in the standard region, judging that the amount of the refrigerants is proper, if the exhaust pressure P0 of the compressor (2) is greater than the maximum of the standard region, judging that the amount of the refrigerants is too much, and if the exhaust pressure P0 of the compressor (2) is less than the minimum of the standard region, judging that the amount of the refrigerants is insufficient. The method is accurate, visualized and convenient.