A distributed algorithm called P-REMiT is proposed for building an energy-efficient multicast tree in ad hoc networks. The P-REMiT uses the probability method to balance the Total Energy Consumption (TEC) and System Lifetime (SL) of multicast tree. It gets the better performance than SREMiT on metrics about system life and also obtains the better performance than L-REMiT on metrics about TEC. It improves SL of multicast tree efficiently with little sacrifice on TEC and has good convergence.