The invention discloses a detecting method of air conditioner hot load and refrigerant mass flow rate, which includes steps of acquiring air inlet enthalpy value and air outlet enthalpy value of an air conditioner; acquiring a first enthalpy difference according to the air inlet enthalpy value and the air outlet enthalpy value; acquiring air volume of a fan; acquiring air conditioner heat load according to the first enthalpy difference and the air volume of the fan; acquiring the enthalpy value of a condenser fluid outlet and enthalpy value of an evaporator gas outlet; acquiring a second enthalpy difference according to the enthalpy value at the condenser fluid outlet and the enthalpy value of the evaporate gas outlet; according to the mass flow formula, calculating and acquiring the refrigerant mass flow rate. The detecting method of air conditioner hot load and refrigerant mass flow rate realizes the calculation of the enthalpy difference and the blast volume while realizes the calculation of refrigerant mass flow rate according to the enthalpy difference and the heat load; according to the feedback heat load signal and the refrigerant mass flow rate signal, the performance management of the air conditioning system and the heat management system of the finished automobile is effectively promoted.